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  • 1. Alam, MT
    et al.
    Yamada, T
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Ikai, A
    The importance of being knotted: Effects of the C-terminal knot structure on enzymatic and mechanical properties of bovine carbonic anhydrase II2003In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 84, no 2, 159A-159A p.Conference paper (Other academic)
  • 2.
    Alam, M.T.
    et al.
    Laboratory of Biodynamics, Grad. Sch. of Biosci. and Biotech., Tokyo Inst. of Technol., 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
    Yamada, T.
    Laboratory of Biodynamics, Grad. Sch. of Biosci. and Biotech., Tokyo Inst. of Technol., 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Ikai, A.
    Laboratory of Biodynamics, Grad. Sch. of Biosci. and Biotech., Tokyo Inst. of Technol., 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
    The importance of being knotted: Effects of the C-terminal knot structure on enzymatic and mechanical properties of bovine carbonic anhydrase II12002In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 519, no 1-3, 35-40 p.Article in journal (Refereed)
    Abstract [en]

    In order to better understand the contribution of the knotted folding pattern to the enzymatic and mechanical properties of carbonic anhydrases, we replaced Gln-253 of bovine carbonic anhydrase II with Cys, which allowed us to measure the mechanical strength of the protein against tensile deformation by avoiding knot tightening. The expressed protein, to our surprise, turned out to contain two conformational isomers, one capable of binding an enzymatic inhibitor and the other not, which led to their separation through affinity chromatography. In near- and far-UV circular dichroism and fluorescence spectra, the separated conformers were very similar to each other and to the wild-type enzyme, indicating that they both had native-like conformations. We describe new evidence which supports the notion that the difference between the two conformers is likely to be related to the completeness of the C-terminal knot formation. © 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.

  • 3.
    Almstedt, Karin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Lundqvist, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology . Linköping University, The Institute of Technology.
    Carlsson, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Bioinformatics . Linköping University, The Institute of Technology.
    Karlsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Persson, Bengt
    Linköping University, Department of Physics, Chemistry and Biology, Bioinformatics . Linköping University, The Institute of Technology.
    Jonsson, Bengt-Harald
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology . Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Unfolding a folding disease: folding, misfolding and aggregation of the marble brain syndrome-associated mutant H107Y of human carbonic anhydrase II2004In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 342, no 2, 619-633 p.Article in journal (Refereed)
    Abstract [en]

    Most loss-of-function diseases are caused by aberrant folding of important proteins. These proteins often misfold due to mutations. The disease marble brain syndrome (MBS), known also as carbonic anhydrase II deficiency syndrome (CADS), can manifest in carriers of point mutations in the human carbonic anhydrase II (HCA II) gene. One mutation associated with MBS entails the His107Tyr substitution. Here, we demonstrate that this mutation is a remarkably destabilizing folding mutation. The loss-of-function is clearly a folding defect, since the mutant shows 64% of CO2 hydration activity compared to that of the wild-type at low temperature where the mutant is folded. On the contrary, its stability towards thermal and guanidine hydrochloride (GuHCl) denaturation is highly compromised. Using activity assays, CD, fluorescence, NMR, cross-linking, aggregation measurements and molecular modeling, we have mapped the properties of this remarkable mutant. Loss of enzymatic activity had a midpoint temperature of denaturation (Tm) of 16 °C for the mutant compared to 55 °C for the wild-type protein. GuHCl-denaturation (at 4 °C) showed that the native state of the mutant was destabilized by 9.2 kcal/mol. The mutant unfolds through at least two equilibrium intermediates; one novel intermediate that we have termed the molten globule light state and, after further denaturation, the classical molten globule state is populated. Under physiological conditions (neutral pH; 37 °C), the His107Tyr mutant will populate the molten globule light state, likely due to novel interactions between Tyr107 and the surroundings of the critical residue Ser29 that destabilize the native conformation. This intermediate binds the hydrophobic dye 8-anilino-1-naphthalene sulfonic acid (ANS) but not as strong as the molten globule state, and near-UV CD reveals the presence of significant tertiary structure. Notably, this intermediate is not as prone to aggregation as the classical molten globule. As a proof of concept for an intervention strategy with small molecules, we showed that binding of the CA inhibitor acetazolamide increases the stability of the native state of the mutant by 2.9 kcal/mol in accordance with its strong affinity. Acetazolamide shifts the Tm to 34 °C that protects from misfolding and will enable a substantial fraction of the enzyme pool to survive physiological conditions.

  • 4.
    Almstedt, Karin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Mårtensson, Lars-Göran
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Thermodynamic interrogation of a folding disease. Mutant mapping of position 107 in human carbonic anhydrase II linked to marble brain disease.2008In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 47, no 5, 1288-1298 p.Article in journal (Refereed)
    Abstract [en]

    Marble brain disease (MBD) also known as Guibaud−Vainsel syndrome is caused by autosomal recessive mutations in the human carbonic anhydrase II (HCA II) gene. HCA II is a 259 amino acid single domain enzyme and is dominated by a 10-stranded β-sheet. One mutation associated with MBD entails the H107Y substitution where H107 is a highly conserved residue in the carbonic anhydrase protein family. We have previously demonstrated that the H107Y mutation is a remarkably destabilizing folding mutation [Almstedt et al. (2004) J. Mol. Biol. 342, 619−633]. Here, the exceptional destabilization by the H107Y mutation has been further investigated. A mutational survey of position H107 and a neighboring conserved position E117 has been performed entailing the mutants H107A, H107F, H107N, E117A and the double mutants H107A/E117A and H107N/E117A. All mutants were severely destabilized versus GuHCl and heat denaturation. Thermal denaturation and GuHCl phase diagram and ANS analyses showed that the mutants shifted HCA II toward populating ensembles of intermediates of molten globule type under physiological conditions. The native state stability of the mutants was in the following order:  wt > H107N > E117A > H107A > H107F > H107Y > H107N/E117A > H107A/E117A. In conclusion:  (i) H107N is least destabilizing likely due to compensatory H-bonding ability of the introduced Asn residue. (ii) Double mutant cycles surprisingly reveal additive destabilization of H107N and E117A showing that H107 and E117 are independently stabilizing the folded protein. (iii) H107Y and H107F are exceptionally destabilizing due to bulkiness of the side chains whereas H107A is more accommodating, indicating long-range destabilizing effects of the natural pathogenic H107Y mutation.

  • 5.
    Almstedt, Karin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Rafstedt, Therese
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Supuran, Claudiu T
    University of Florence.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Small-Molecule Suppression of Misfolding of Mutated Human Carbonic Anhydrase II Linked to Marble Brain Disease2009In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 48, no 23, 5358-5364 p.Article in journal (Refereed)
    Abstract [en]

    Carbonic anhydrase II deficiency syndrome or Marble brain disease (MBD) is caused by autosomal recessive mutations in the human carbonic anhydrase II (HCA II) gene. Here we report a small-molecule stabilization study of the exceptionally destabilized HCA II mutant H107Y employing inhibitors based on p-aminobenzoyisulfonamide compounds and 1,3,4-thiadiazolylsulfonamides as well as amino acid activators. Protein stability assays showed a significant stabilization by the aromatic sulfonamide inhibitors when present at 10 mu M concentration, providing shifts of the midpoint of thermal denaturation between 10 degrees C and 16 degrees C and increasing the free energies of denaturation 0.5-3.0 kcal/mol as deduced from GuHCl denaturation. This study could be used as a starting point for the design of small-molecule folding modulators and possibly autoactivatable molecules for suppression of misfolding of destabilized HCA II mutants.

  • 6. Andersson, D.
    et al.
    Hammarström, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Cofactor-induced refolding: Refolding of molten globule carbonic anhydrase induced by Zn(II) and Co(II)2001In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 40, no 9, 2653-2661 p.Article in journal (Refereed)
    Abstract [en]

    The stability versus unfolding to the molten globule intermediate of bovine carbonic anhydrase II (BCA II) in guanidine hydrochloride (GuHCl) was found to depend on the metal ion cofactor [Zn(II) or Co(II)], and the apoenzyme was observed to be least stable. Therefore, it was possible to find a denaturant concentration (1.2 M GuHCl) at which refolding from the molten globule to the native state could be initiated merely by adding the metal ion to the apo molten globule. Thus, refolding could be performed without changing the concentration of the denaturant. The molten globule intermediate of BCA II could still bind the metal cofactor. Cofactor-effected refolding from the molten globule to the native state can be summarized as follows: (1) initially, the metal ion binds to the molten globule, (2) compaction of the metal-binding site region is then induced by the metal ion binding, (3) a functioning active center is formed, and (4) finally, the native tertiary structure is generated in the outer parts of the protein.

  • 7.
    Andersson, Dick
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Freskgård, Per-Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Contribution of tryptophan residues to the CD spectrum of the extracellular domain of human tissue factor: Application in folding studies and prediction of secondary structure2001In: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 268, no 4, 1118-1128 p.Article in journal (Refereed)
    Abstract [en]

    The contribution to the circular dichroism (CD) spectrum made by each of the four Trp residues in the extracellular domain of human tissue factor, sTF (s designates soluble), was determined from difference CD spectra. The individual Trp CD spectra showed that all four residues contributed to the CD spectrum in almost the entire wavelength region investigated (180-305 nm). The sum of the individual spectra of each Trp residue in the near-UV region was qualitatively identical to the wild-type spectrum, clearly demonstrating that the Trp residues are the major contributors to the spectrum in this wavelength region. Trp CD bands interfere with the peptide bands in the far-UV region, leading to uncertainty in the predictions of the amounts of various types of secondary structure. Accordingly, the best prediction of secondary sTF structure content was achieved using a hypothetical Trp-free CD spectrum obtained after subtraction of all individual Trp spectra from the wild-type spectrum. The mutated Trp residues were also exploited as intrinsic probes to monitor the formation of local native-like tertiary structure by kinetic near-UV CD measurements. The global folding reaction was followed in parallel with a novel functional assay that registered the recovery of cofactor activity, i.e. stimulation of the amidolytic activity of Factor VIIa. From these measurements, it was found that sTF appears to regain FVIIa cofactor activity before the final side-chain packing of the Trp residues. The combined kinetic refolding results suggest that the compact asymmetric environments of the individual Trp residues in sTF are formed simultaneously, leading to the conclusion that the native tertiary structure of the whole protein is formed in a cooperative manner.

  • 8.
    Asplund, Gunilla
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Borén, Hans
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Grimvall, Anders
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Soil Peroxidase-Mediated Chlorination of Fulvic Acid1991In: Humic substances in the aquatic and terrestrial environment : proceedings of an international symposium, Linköping, Sweden, August 21-23, 1989 / [ed] B. Allard, H. Borén and A. Grimvall, Berlin Heidelberg New York: Springer, 1991, 474-483 p.Chapter in book (Refereed)
    Abstract [en]

    Humic matter has recently been shown to contain considerable quantities of naturally produced organohalogens. The present study investigated the possibility of a non-specific, enzymatically mediated halogenation of organic matter in soil. The results showed that, in the presence of chloride and hydrogen peroxide, the enzyme chloroperox1dase (CPO) from the fungus Caldariomyces fumago catalyzes chlorination of fulvic acid. At pH 2.5 - 6.0, the chlorine to fulvic acid ratio in the tested sample was elevated from 12 mg/g to approximately 40-50 mg/g. It was also shown that this reaction can take place at chloride and hydrogen peroxide concentrations found in the environment. An extract from spruce forest soil was shown to have a measurable chlorinating capacity. The activity of an extract of 0.5 kg soil corresponded to approximately 0.3 enzyme units, measured as CPO activity. Enzymatically mediated halogenation of humic substances may be one of the mechanisms explaining the w1despread occurrence of adsorbable organic halogens (AOX) in soil and water.

  • 9.
    Babu Moparthi, Satish
    et al.
    Aix Marseille University, France.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Vincentelli, Renaud
    University of Aix Marseille, France.
    Jonsson, Bengt-Harald
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Wenger, Jerome
    Aix Marseille University, France.
    Differential conformational modulations of MreB folding upon interactions with GroEL/ES and TRiC chaperonin components2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, no 28386Article in journal (Refereed)
    Abstract [en]

    Here, we study and compare the mechanisms of action of the GroEL/GroES and the TRiC chaperonin systems on MreB client protein variants extracted from E. coli. MreB is a homologue to actin in prokaryotes. Single-molecule fluorescence correlation spectroscopy (FCS) and time-resolved fluorescence polarization anisotropy report the binding interaction of folding MreB with GroEL, GroES and TRiC. Fluorescence resonance energy transfer (FRET) measurements on MreB variants quantified molecular distance changes occurring during conformational rearrangements within folding MreB bound to chaperonins. We observed that the MreB structure is rearranged by a binding-induced expansion mechanism in TRiC, GroEL and GroES. These results are quantitatively comparable to the structural rearrangements found during the interaction of beta-actin with GroEL and TRiC, indicating that the mechanism of chaperonins is conserved during evolution. The chaperonin-bound MreB is also significantly compacted after addition of AMP-PNP for both the GroEL/ES and TRiC systems. Most importantly, our results showed that GroES may act as an unfoldase by inducing a dramatic initial expansion of MreB (even more than for GroEL) implicating a role for MreB folding, allowing us to suggest a delivery mechanism for GroES to GroEL in prokaryotes.

  • 10.
    Babu Moparthi, Satish
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering. Institut Fresnel, CNRS UMR 7249, Aix-Marseille Université, Marseille, France.
    Sjölander, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Villebeck, Laila
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology. Linköping University, The Institute of Technology.
    Jonsson, Bengt-Harald
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Transient conformational remodeling of folding proteins by GroES - Individually and in concert with GroEL2014In: Journal of chemical biology, ISSN 1864-6158, E-ISSN 1864-6166, Vol. 7, no 1, 1-15 p.Article, review/survey (Refereed)
    Abstract [en]

    The commonly accepted dogma of the bacterial GroE chaperonin system entails protein folding mediated by cycles of several ATP-dependent sequential steps where GroEL interacts with the folding client protein. In contrast, we herein report GroES-mediated dynamic remodeling (expansion and compression) of two different protein substrates during folding: the endogenous substrate MreB and carbonic anhydrase (HCAII), a well-characterized protein folding model. GroES was also found to influence GroEL binding induced unfolding and compression of the client protein underlining the synergistic activity of both chaperonins, even in the absence of ATP. This previously unidentified activity by GroES should have important implications for understanding the chaperonin mechanism and cellular stress response. Our findings necessitate a revision of the GroEL/ES mechanism.

  • 11.
    Carlsson, Karin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Freskgard, P.-O.
    Freskgård, P.-O., Protein Biotechnology, Novo Nordisk A/S, Novo Allé, Bagsværd, Denmark, Nuevolution A/S, Rønnegade 8, Copenhagen, Denmark.
    Persson, E.
    Haemostasis Biology, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Svensson, Magdalena
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Probing the interface between factor Xa and tissue factor in the quaternary complex tissue factor-factor VIIa-factor Xa-tissue factor pathway inhibitor2003In: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 270, no 12, 2576-2582 p.Article in journal (Refereed)
    Abstract [en]

    Blood coagulation is triggered by the formation of a complex between factor VIIa (FVIIa) and its cofactor, tissue factor (TF). TF-FVIIa is inhibited by tissue factor pathway inhibitor (TFPI) in two steps: first TFPI is bound to the active site of factor Xa (FXa), and subsequently FXa-TFPI exerts feedback inhibition of TF-FVIIa. The FXa-dependent inhibition of TF-FVIIa activity by TFPI leads to formation of the quaternary complex TF-FVIIa-FXa-TFPI. We used site-directed fluorescence probing to map part of the region of soluble TF (sTF) that interacts with FXa in sTF-FVIIa-FXa-TFPI. We found that the C-terminal region of sTF, including positions 163, 166, 200 and 201, is involved in binding to FXa in the complex, and FXa, most likely via its Gla domain, is also in contact with the Gla domain of FVIIa in this part of the binding region. Furthermore, a region that includes the N-terminal part of the TF2 domain and the C-terminal part of the TF1 domain, i.e. the residues 104 and 197, participates in the interaction with FXa in the quaternary complex. Moreover, comparisons of the interaction areas between sTF and FX(a) in the quaternary complex sTF-FVIIa-FXa-TFPI and in the ternary complexes sTF-FVII-FXa or sTF-FVIIa-FX demonstrated large similarities.

  • 12.
    Carlsson, Karin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Osterlund, Maria
    University Holding, Teknikringen 7, SE-581 83 Linköping, Sweden.
    Persson, Egon
    Vascular Biochemistry, Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Måløv, Denmark.
    Freskgard, P.-O.
    Freskgård, P.-O., Protein Biotechnology, Novo Nordisk A/S, Novo Allé, DK-2880 Bagsværd, Denmark, Molecular Biology, Maxygen ApS, DK-2970, Hørsholm, Denmark.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Svensson, Magdalena
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Site-directed fluorescence probing to dissect the calcium-dependent association between soluble tissue factor and factor VIIa domains2003In: Biochimica et Biophysica Acta - Proteins and Proteomics, ISSN 1570-9639, E-ISSN 1878-1454, Vol. 1648, no 1-2, 12-16 p.Article in journal (Refereed)
    Abstract [en]

    We have used the site-directed labeling approach to study the Ca 2+-dependent docking of factor VIIa (FVIIa) to soluble tissue factor (sTF). Nine Ca2+ binding sites are located in FVIIa and even though their contribution to the overall binding between TF and FVIIa has been thoroughly studied, their importance for local protein-protein interactions within the complex has not been determined. Specifically we have monitored the association of the ?-carboxyglutamic acid (Gla), the first EGF-like (EGF1), and the protease domains (PD) of FVIIa to sTF. Our results revealed that complex formation between sTF and FVIIa during Ca2+ titration is initiated upon Ca2+ binding to EGF1, the domain containing the site of highest Ca2+ affinity. Besides we showed that a Ca 2+-loaded Gla domain is required for an optimal association of all domains of FVIIa to sTF. Ca2+ binding to the PD seems to be of some importance for the docking of this domain to sTF. © 2003 Elsevier Science B.V. All rights reserved.

  • 13.
    Carlsson, Karin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Persson, Egon
    Haemostasis Biochemistry, Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Måløv, Denmark.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Svensson, Magdalena
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Inhibitors of factor VIIa affect the interface between the protease domain and tissue factor2006In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 349, no 3, 1111-1116 p.Article in journal (Refereed)
    Abstract [en]

    Blood coagulation is triggered by the formation of a complex between factor VIIa (FVIIa) and its cofactor, tissue factor (TF). The γ-carboxyglutamic acid-rich domain of FVIIa docks with the C-terminal domain of TF, the EGF1 domain of FVIIa contacts both domains of TF, and the EGF2 domain and protease domain (PD) form a continuous surface that sits on the N-terminal domain of TF. Our aim was to investigate the conformational changes that occur in the sTF·PD binding region when different types of inhibitors, i.e., one active-site inhibitor (FFR-chloromethyl ketone (FFR)), two different peptide exosite inhibitors (E-76 and A-183), and the natural inhibitor tissue factor pathway inhibitor (TFPI), were allowed to bind to FVIIa. For this purpose, we constructed two sTF mutants (Q37C and E91C). By the aid of site-directed labeling technique, a fluorescent label was attached to the free cysteine. The sTF·PD interface was affected in position 37 by the binding of FFR, TFPI, and E-76, i.e., a more compact structure was sensed by the probe, while for position 91 located in the same region no change in the surrounding structure was observed. Thus, the active site inhibitors FFR and TFPI, and the exosite inhibitor E-76 have similar effects on the probe in position 37 of sTF, despite their differences in size and inhibition mechanism. The allosteric changes at the active site caused by binding of the exosite inhibitor E-76 in turn induce similar conformational changes in the sTF·PD interface as does the binding of the active site inhibitors. A-183, on the other hand, did not affect position 37 in sTF, indicating that the A-183 inhibition mechanism is different from that of E-76.

  • 14.
    Carlsson, Karin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Persson, Egon
    Haemostasis Biochemistry, Novo Nordisk A/S, DK-2760 Måløv, Denmark.
    Østergaard, Henrik
    Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway.
    Lindgren, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Svensson, Magdalena
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Effects on the conformation of FVIIa by sTF and Ca(2+) binding: Studies of fluorescence resonance energy transfer and quenching2011In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 413, no 4, 545-549 p.Article in journal (Refereed)
    Abstract [en]

    The apparent length of FVIIa in buffer solution was estimated by a FRET analysis. Two fluorescent probes, fluorescein linked to an inhibitor (FPR-chloromethyl ketone) and a rhodamine derivative (tetramethylrhodamine-5-maleimide), were covalently attached to FVIIa. The binding site of fluorescein was in the PD whereas rhodamine was positioned in the Gla domain, thus allowing a length measure over approximately the whole extension of the protein. From the FRET measurements the distances between the two probes were determined to 61.4 for free FVIIa and 65.5 Å for FVIIa bound to the soluble TF (sTF). Thus, the apparent distance from the FRET analysis was shown to increase with 4 Å upon formation of a complex with sTF in solution. However, by considering how protein dynamics, based on recently published molecular dynamics simulations of FVIIa and sTF:FVIIa (Ohkubo et al., 2010 J. Thromb. Haemost. 8, 1044-1053), can influence the apparent  fluorescence signal our calculations indicated that the global average conformation of active-site inhibited FVIIa is nearly unaltered upon ligation to sTF.

    Moreover, it is known that Ca2+ binding leads to activation of FVIIa, and we have for the first time demonstrated conformational changes in the environment of the active site upon Ca2+ binding by direct measurements, previously suggested based on indirect measurements (Persson & Petersen, 1995 Eur. J. Biochem. 234, 293-300). Interestingly, this Ca2+-induced conformational change can be noted even in the presence of an inhibitor. By forming the sTF:FVIIa complex the conformational change of the active site is further developed, leading to a more inaccessible active-site located probe.

  • 15.
    Carlsson, Uno
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Hammarström, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Lindgren, M
    Persson, M
    Freskgård, Per-Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Mårtensson, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Andersson, D
    Jonsson, Bengt-Harald
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology .
    Svensson, Magdalena
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Aggregation is site-specific in carbonic anhydrase and is prevented by GroEL: The interaction leads to a more flexible structure of both the protein substrate and the chaperonin.2000In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 78, no 1, 202Pos- p.Conference paper (Other academic)
  • 16.
    Carlsson, Uno
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Magnusson, Thomas
    Linköping University, Department of Management and Engineering, Project management, Innovations and Entrepreneurship . Linköping University, The Institute of Technology.
    Mårtensson, Lars-Göran
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Sunnerhagen, Maria
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Svensson, Magdalena
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Tibell, Lena
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    To design a novel protein: A CDIO experience in Molecular Biotechnology at Linköping University2006Conference paper (Other academic)
  • 17.
    Hammarström, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Is the unfolded state the Rosetta Stone of the protein folding problem?2000In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 276, no 2, 393-398 p.Article in journal (Refereed)
    Abstract [en]

    Solving the protein folding problem is one of the most challenging tasks in the post genomic era. Identification of folding-initiation sites is very important in order to understand the protein folding mechanism. Detection of residual structure in unfolded proteins can yield important clues to the initiation sites in protein folding. A substantial number of studied proteins possess residual structure in hydrophobic regions clustered together in the protein core. These stable structures can work as seeds in the folding process. In addition, local preferences for secondary structure in the form of turns for ▀-sheet initiation and helical turns for a-helix formation can guide the folding reaction. In this respect the unfolded states, studied at increasing structural resolution, can be the Rosetta Stone of the protein folding problem. (C) 2000 Academic Press.

  • 18.
    Hammarström, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Kalman, B.
    Jonsson, Bengt-Harald
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology .
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Pyrene Excimer Fluorescence as a Proximity Probe for Investigation of Residual Structure in the Unfolded State of Human Carbonic Anhydrase II1997In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 420, 63-68 p.Article in journal (Refereed)
  • 19.
    Hammarström, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Owenius, Rikard
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Mårtensson, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Lindgren, M
    High-resolution probing of local conformational changes in proteins by the use of multiple labeling: Unfolding and self-assembly of human carbonic anhydrase II monitored by spin, fluorescent, and chemical reactivity probes2001In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 80, no 6, 2867-2885 p.Article in journal (Refereed)
    Abstract [en]

    Two different spin labels, N-(1-oxyl-2,2,5,5-tetramethyl-3-pyrrolidinyl)iodoacetamide (IPSL) and (1-oxyl-2.2,5,5-tetramethylpyrroline-3-methyl) methanethiosulfonate (MTSSL), and two different fluorescent labels 5-((((2-iodoacetyl)amino)ethyl)amino)naphtalene-1 -sulfonic acid (IAEDANS) and 6-bromoacetyl-2-dimetylaminonaphtalene (BADAN), were attached to the introduced C79 in human carbonic anhydrase (HCA II) to probe local structural changes upon unfolding and aggregation, HCA II unfolds in a multi-step manner with an intermediate state populated between the native and unfolded states. The spin label IPSL and the fluorescent label IAEDANS reported on a substantial change in mobility and polarity at both unfolding transitions at a distance of 7.4-11.2 Angstrom from the backbone of position 79. The shorter and less flexible labels BADAN and MTSSL revealed less pronounced spectroscopic changes in the native-to-intermediate transition, 6.6-9.0 Angstrom from the backbone. At intermediate guanidine (Gu)-HCl concentrations the occurrence of soluble but irreversibly aggregated oligomeric protein was identified from refolding experiments. At similar to1 M Gu-HCl the aggregation was found to be essentially complete. The size and structure of the aggregates could be varied by changing the protein concentration. EPR measurements and line-shape simulations together with fluorescence lifetime and anisotropy measurements provided a picture of the self-assembled protein as a disordered protein structure with a representation of both compact as well as dynamic and polar environments at the site of the molecular labels. This suggests that a partially folded intermediate of HCA II self-assembles by both local unfolding and intermolecular docking of the intermediates vicinal to position 79. The aggregates were determined to be 40-90 Angstrom in diameter depending on the experimental conditions and spectroscopic technique used.

  • 20.
    Hammarström, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Persson, M
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Compactness measurements at unfolding of carbonic anhydrase by Trp-AEDANS fluorescence energy transfer. Evidence for forced unfolding by GroEL.2000In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 78, no 1, 203Pos- p.Conference paper (Other academic)
  • 21.
    Hammarström, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Persson, Malin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Protein compactness measured by fluorescence resonance energy transfer - Human carbonic anhydrase II Is considerably expanded by the interaction of GroEL2001In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 276, no 24, 21765-21775 p.Article in journal (Refereed)
    Abstract [en]

    Nine single-cysteine mutants were labeled with 5-(2-iodoacetylaminoethylamino)naphthalene-1-sulfonic acid, an efficient acceptor of Trp fluorescence in fluorescence resonance energy transfer. The ratio between the fluorescence intensity of the 5-(2-acetylaminoethylamino)naphthalene-1-sulfonic acid (AEDANS) moiety excited at 295 nm (Trp absorption) and 350 nn (direct AEDANS absorption) was used to estimate the average distances between the seven Trp residues in human carbonic anhydrase II (HCA II) and the AEDANS label, Guanidine HCl denaturation of the HCA II variants was also performed to obtain a curve that reflected the compactness of the protein at various stages of the unfolding, which could serve as a scale of the expansion of the protein. This approach was developed in this study and was used to estimate the compactness of HCA II during heat denaturation and interaction with GroEL, It was shown that thermally induced unfolding of HCA II proceeded only to the molten globule state. Reaching this state was sufficient to allow HCA II to bind to GroEL, and the volume of the molten globule intermediate increased similar to2.2-fold compared with that of the native state. GroEL-bound HCA II expands to a volume three to four times that of the native state (to similar to 117,000 Angstrom (3)), which correlates well with a stretched and loosened-up HCA II molecule in an enlarged GroEL cavity, Recently, we found that HCA II binding causes such an inflation of the GroEL molecule, and this probably represents the mechanism by which GroEL actively stretches its protein substrates apart (Hammarstrom, P., Persson, M., Owenius, R., Lindgren, M., and Carlsson, U. (2000) J. Biol. Chem. 275, 22832-22838), thereby facilitating rearrangement of misfolded structure.

  • 22.
    Hammarström, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Persson, Malin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Freskgård, Per-Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Mårtensson, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Andersson, D.
    Jonsson, Bengt-Harald
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology .
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Structural mapping of an aggregation nucleation site in a molten-globule intermediate1999In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 274, 32897-32903 p.Article in journal (Refereed)
  • 23.
    Hammarström, Per
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Persson, Malin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Owenius, Rikard
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Lindgren, M.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Protein substrate binding induces conformational changes in the chaperonin GroEL: A suggested mechanism for unfoldase activity2000In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 275, no 30, 22832-22838 p.Article in journal (Refereed)
    Abstract [en]

    Chaperonins are molecules that assist proteins during folding and protect them from irreversible aggregation. We studied the chaperonin GroEL and its interaction with the enzyme human carbonic anhydrase II (HCA II), which induces unfolding of the enzyme. We focused on conformational changes that occur in GroEL during formation of the GroEL-HCA II complex. We measured the rate of GroEL cysteine reactivity toward iodo[2-(14)C]acetic acid and found that the cysteines become more accessible during binding of a cysteine free mutant of HCA II. Spin labeling of GroEL with N-(1-oxy1-2,2,5,5-tetramethyl-3-pyrrolidinyl)iodoacetamide revealed that this additional binding occurred because buried cysteine residues become accessible during HCA II binding. In addition, a GroEL variant labeled with 6-iodoacetamidofluorescein exhibited decreased fluorescence anisotropy upon HCA II binding, which resembles the effect of GroES/ATP binding. Furthermore, by producing cysteine-modified GroEL with the spin label N-(1-oxyl-2,2,5,5-tetramethyl-3-pyrrolidinyl)iodoacetamide and the fluorescent label 5-((((2-iodoacetyl)amino)ethyl)amino)naphthalene-1-sulfonic acid, we detected increases in spin-label mobility and fluorescence intensity in GroEL upon HCA II binding. Together, these results show that conformational changes occur in the chaperonin as a consequence of protein substrate binding. Together with previous results on the unfoldase activity of GroEL, we suggest that the chaperonin opens up as the substrate protein binds. This opening mechanism may induce stretching of the protein, which would account for reported unfoldase activity of GroEL and might explain how GroEL can actively chaperone proteins larger than HCA II.

  • 24.
    Huber, M
    et al.
    Leiden Univ, Dept Mol Phys, NL-2300 RA Leiden, Netherlands Inst Phys & Measurement Technol, Linkoping, Sweden.
    Owenius, Rikard
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Hammarström, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Mårtensson, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    High-field (95 GHz) EPR on spin labels in human carbonic anhydrase II: Perspectives of pulsed and CW EPR2000In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 78, no 1, 182Pos- p.Conference paper (Other academic)
  • 25.
    Karabencheva-Christova, Tatyana G
    et al.
    Northumbria University, England.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Balali-Mood, Kia
    University of Oxford, England.
    Black, Gary W.
    Northumbria University, England.
    Christov, Christo Z.
    Northumbria University, England.
    Conformational Effects on the Circular Dichroism of Human Carbonic Anhydrase II: A Multilevel Computational Study2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 2Article in journal (Refereed)
    Abstract [en]

    Circular Dichroism (CD) spectroscopy is a powerful method for investigating conformational changes in proteins and therefore has numerous applications in structural and molecular biology. Here a computational investigation of the CD spectrum of the Human Carbonic Anhydrase II (HCAII), with main focus on the near-UV CD spectra of the wild-type enzyme and it seven tryptophan mutant forms, is presented and compared to experimental studies. Multilevel computational methods (Molecular Dynamics, Semiempirical Quantum Mechanics, Time-Dependent Density Functional Theory) were applied in order to gain insight into the mechanisms of interaction between the aromatic chromophores within the protein environment and understand how the conformational flexibility of the protein influences these mechanisms. The analysis suggests that combining CD semi empirical calculations, crystal structures and molecular dynamics (MD) could help in achieving a better agreement between the computed and experimental protein spectra and provide some unique insight into the dynamic nature of the mechanisms of chromophore interactions.

  • 26.
    Karlsson, Martin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Adsorption at the liquid-solid Interface - Influence of protein stability on conformational changes2007In: Encyclopedia of surfaces and colloid science / [ed] Ponisseril Somasundaran, Taylor & Francis, 2007, 2, Vol. 1Chapter in book (Refereed)
    Abstract [en]

    Protein adsorption has large implications in a variety of fields and can be both a problem and an asset. Most often protein adsorption is accompanied by structural changes in the adsorbed protein. The degree and rate of these changes are dependent on the surface, conditions during adsorption and experimental set up as well as of intrinsic properties of the protein. The effect of conformational changes influences both practical applications and experimental results in studies of protein adsorption at the liquid/solid interface. The intrinsic property of the protein that is most instrumental for conformational changes upon adsorption is the stability of the protein. Hence, large efforts have been directed towards analysis of how both the nature of surfaces and conditions influence the stability of proteins upon adsorption. Less work has been focused on the reversed view, i.e. how the stability of proteins influences adsorption, the rate and degree of the subsequent conformational changes as well as the effects of these changes. However, the increasing use of proteins in a variety of medical and biotechnological applications requires a deeper knowledge of the importance and effects of stabilizing interactions in the protein structure. Engineered stabilized proteins that are less affected by surface interactions should be of potential use for various practical purposes.

  • 27.
    Karlsson, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Protein adsorption orientation in the light of fluorescent probes: mapping of the interaction between site-directly labeled human carbonic anhydrase II and silica nanoparticles2005In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 88, no 5, 3536-3544 p.Article in journal (Refereed)
    Abstract [en]

    Little is known about the direction and specificity of protein adsorption to solid surfaces, a knowledge that is of great importance in many biotechnological applications. To resolve the direction in which a protein with known structure and surface potentials binds to negatively charged silica nanoparticles, fluorescent probes were attached to different areas on the surface of the protein human carbonic anhydrase II. By this approach it was clearly demonstrated that the adsorption of the native protein is specific to limited regions at the surface of the N-terminal domain of the protein. Furthermore, the adsorption direction is strongly pH-dependent. At pH 6.3, a histidine-rich area around position 10 is the dominating adsorption region. At higher pH values, when the histidines in this area are deprotonated, the protein is also adsorbed by a region close to position 37, which contains several lysines and arginines. Clearly the adsorption is directed by positively charged areas on the protein surface toward the negatively charged silica surface at conditions when specific binding occurs.

  • 28.
    Karlsson, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Ekeroth, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Elwing, Hans
    Department of Cell and Molecular Biology, Göteborg University, Sweden.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Reduction of irreversible protein adsorption on solid surfaces by protein engineering for increased stability2005In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 280, no 27, 25558-25564 p.Article in journal (Refereed)
    Abstract [en]

    The influence of protein stability on the adsorption and desorption behavior to surfaces with fundamentally different properties (negatively charged, positively charged, hydrophilic, and hydrophobic) was examined by surface plasmon resonance measurements. Three engineered variants of human carbonic anhydrase II were used that have unchanged surface properties but large differences in stability. The orientation and conformational state of the adsorbed protein could be elucidated by taking all of the following properties of the protein variants into account: stability, unfolding, adsorption, and desorption behavior. Regardless of the nature of the surface, there were correlation between (i) the protein stability and kinetics of adsorption, with an increased amplitude of the first kinetic phase of adsorption with increasing stability; (ii) the protein stability and the extent of maximally adsorbed protein to the actual surface, with an increased amount of adsorbed protein with increasing stability; (iii) the protein stability and the amount of protein desorbed upon washing with buffer, with an increased elutability of the adsorbed protein with increased stability. All of the above correlations could be explained by the rate of denaturation and the conformational state of the adsorbed protein. In conclusion, protein engineering for increased stability can be used as a strategy to decrease irreversible adsorption on surfaces at a liquid-solid interface.

  • 29.
    Karlsson, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Mårtensson, Lars-Göran
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Jonsson, Bengt-Harald
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Adsorption of human carbonic anhydrase II variants to silica nanoparticles occur stepwise: binding is followed by successive conformational changes to a molten-globule-like state2000In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 16, no 22, 8470-8479 p.Article in journal (Refereed)
    Abstract [en]

    The surface adsorption behavior of protein variants of the enzyme human carbonic anhydrase II (HCA II) to silica nanoparticles has been investigated. Various destabilized mutants were produced by site-directed mutagenesis of amino acids located in the interior of the protein. The silica particles induced a molten-globule-like state in all of the variants. All protein variants initially adsorbed to the particles, and then underwent conformational rearrangements in a stepwise manner, as indicated by the loss of activity and the subsequent loss of tertiary structure. Activity, CD, and ANS fluorescence measurements showed that a decrease in the global stability of the protein is strongly correlated to increased rates of conformational change following particle adsorption. In contrast to unfolding processes induced by chemical denaturants or heat, in the transition to the molten-globule-like state induced by the silica particles, the active site region unfolds before the majority of the tertiary interactions are broken.

  • 30.
    Karlsson, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Mårtensson, Lars-Göran
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Karlsson, Carin
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Denaturant-assisted formation of a stabilizing disulfide bridge from engineered cysteines in nonideal conformations2005In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 44, no 9, 3487-3493 p.Article in journal (Refereed)
    Abstract [en]

    The engineered disulfide bridge A23C/L203C in human carbonic anhydrase II, inserted from homology modeling of Neisseria gonorrhoeae carbonic anhydrase, significantly stabilizes the native state of the protein. The inserted cysteine residues are placed in the interior of the structure, and because of the conformationally restrained localization, the protein is expressed in the reduced state and the cysteines are not readily oxidized. However, upon exposure to low concentrations of denaturant (0.6 M guanidine hydrochloride), corresponding to the lower part of the denaturation curve for the first unfolding transition, the oxidation rate of correctly formed disulfide bridges was markedly increased. By entropy estimations it appears that the increased flexibility, induced by the denaturant, enables the cysteines to find each other and hence to form the disulfide bridge. The outlined strategy of facilitating formation of disulfide bonds by addition of adjusted concentrations of a denaturant should be applicable to other proteins in which engineered cysteine residues are located in nonideal conformations. Moreover, a S99C/V242C variant was constructed, in which the cysteine residues are located on the surface. In this mutant the disulfide bridge was spontaneously formed and the native state was considerably stabilized (midpoint concentration of unfolding was increased from 1.0 to 1.4 M guanidine hydrochloride).

  • 31.
    Karlsson, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Mårtensson, Lars-Göran
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Olofsson, Patrik
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Circumnavigating misfolding traps in the energy landscape through protein engineering: suppression of molten globule and aggregation in carbonic anhydrase2004In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 43, no 21, 6803-6807 p.Article in journal (Refereed)
    Abstract [en]

    The native state of the enzyme human carbonic anhydrase (HCA II) has been stabilized by the introduction of a disulfide bond, the oxidized A23C/L203C mutant. This stabilized protein variant undergoes an apparent two-state unfolding process with suppression of the otherwise stable equilibrium, molten-globule intermediate, which is normally very prone to aggregation. Stopped-flow measurements also showed that lower amounts of the transiently occurring molten globule were formed during refolding. This led to a markedly lowered tendency for aggregation during equilibrium denaturing conditions and, more importantly, to significantly higher reactivation yields upon refolding of the fully denatured protein. Thus, a general strategy to circumvent aggregation during the refolding of proteins could be to stabilize the native state of a protein at the expense of partially folded intermediates, thereby shifting the unfolding behavior from a three-state process to a two-state one.

  • 32. Knudsen, J.F.
    et al.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Hammarström, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Sokol, G.H.
    Cantilena, R
    The cyclooxygenase-2 inhibitor celecoxib is a potent inhibitor of human carbonic anhydrase II2004In: Inflammation, ISSN 0360-3997, E-ISSN 1573-2576, Vol. 28, no 5, 285-290 p.Article in journal (Refereed)
    Abstract [en]

    Cyclooxygenase-2 (COX-2) is up-regulated in stromal and inflammatory cells. The inducible COX-2 isoform is expressed during inflammation, in some cancers, and in brain tissue after global and focal ischemia. Tissue acidosis is a dominant factor in inflammation, and contributes to pain and hyperalgesia. Recently, compelling epidemiological and clinical evidence has documented the COX-independent effects of some COX-2 inhibitors (i.e., celecoxib, valdecoxib, and rofecoxib), among these effects are carbonic anhydrase (CA) inhibition. Carbonic anhydrases are zinc metalloenzymes expressed in various cell types, including those of the kidney, where they act as general acid-base catalysts. The kidneys are also known to express the highest concentration of COX-2 messenger ribonucleic acid. Celecoxib, like the prototypic CA inhibitor acetazolamide, is structurally characterized by an unsubstituted sulfonamide moiety. In the present study, we report that celecoxib exhibits the characteristics of a potent CA inhibitor, showing inhibitory human carbonic anhydrase II (hCAII) activity in the nanomolar range. Valdecoxib was relatively less potent. Rofecoxib, which lacks the unsubstituted sulfonamide moiety characteristic of CA inhibitors, showed no significant hCAII inhibitory activity. The current study corroborates our earlier report of structure-activity relationships as predictors of such metabolic events as hyperchloremia, acidosis, and changes in calcium and phosphate disposition, and clinical manifestations associated with CA inhibition reported with celecoxib. These data showing inhibition of hCAII by the unsubstituted sulfonamides celecoxib and valdecoxib, but not by rofecoxib, may have important implications for the elucidation of the mechanisms of action as well as the side effects associated with COX-2 inhibitors. © 2004 Springer Science+Business Media, Inc.

  • 33. Lindgren, M.
    et al.
    Eaton, S.
    Eaton, G
    Jonsson, Bengt-Harald
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology .
    Hammarström, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Svensson, Magdalena
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Electron Spin Echo Decay at a Probe of Aminoxyl Environment in Spin-labeled Mutants of Carbonic Anhydrase1997In: Journal of the Chemical Society. Perkin transactions II, ISSN 0300-9580, 2549-2554 p.Article in journal (Refereed)
  • 34.
    Mishra, Rajesh
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Olofsson, Linus
    Karlsson, Martin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Nicholls, Ian A.
    Hammarström, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    A conformationally isoformic thermophilic protein with high kinetic unfolding barriers2008In: Cellular and Molecular Life Sciences (CMLS), ISSN 1420-682X, E-ISSN 1420-9071, Vol. 65, no 5, 827-839 p.Article in journal (Refereed)
    Abstract [en]

    The basis for the stability of thermophilic proteins is of fundamental interest for extremophile biology. We investigated the folding and unfolding processes of the homotetrameric Thermoanaerobacter brockii alcohol dehydrogenase (TBADH). TBADH subunits were 4.8 kcal/mol less stable towards guanidinium chloride (GdmCl) unfolding compared to urea, indicating ionic modulation of TBADH stability. Strongly denaturing conditions promoted mono-exponential unfolding kinetics with linear dependence on denaturant concentration. Here TBADH unfolded >40-fold slower when extrapolated from urea as compared to GdmCl unfolding. A marked unfolding hysteresis was shown when comparing refolding and unfolding in urea. An unusual biphasic unfolding trajectory with an exceptionally slow phase at intermediate concentrations of GdmCl and urea was also observed. We advocate that TBADH forms two distinctly different tetrameric isoforms, and likely an ensemble of native states. This unusual supramolecular folding behavior has been shown responsible for formation of amyloidotic yeast prion strains and can have functional importance for TBADH. © 2008 Birkhaueser.

  • 35.
    Moparthi, Satish Babu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Fristedt, Rikard
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Mishra, Rajesh
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Almstedt, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Karlsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Chaperone activity of Cyp18 through hydrophobic condensation that enables rescue of transient misfolded molten globule intermediates2010In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 49, no 6, 1137-1145 p.Article in journal (Refereed)
    Abstract [en]

    The single-domain cyclophilin 18 (Cyp18) has long been known to function as a peptidyl-prolyl cis/trans isomerase (PPI) and was proposed by us to also function as a chaperone [Freskgård, P.-O., Bergenhem, N., Jonsson, B.-H., Svensson, M., and Carlsson, U. (1992) Science 258, 466−468]. Later several multidomain PPIs were demonstrated to work as both a peptidyl-prolyl cis/trans isomerase and a chaperone. However, the chaperone ability of Cyp18 has been debated. In this work, we add additional results that show that Cyp18 can both accelerate the rate of refolding and increase the yield of native protein during the folding reaction, i.e., function as both a folding catalyst and a chaperone. Refolding experiments were performed using severely destabilized mutants of human carbonic anhydrase II under conditions where the unfolding reaction is significant and a larger fraction of a more destabilized variant populates molten globule-like intermediates during refolding. A correlation of native state protein stability of the substrate protein versus Cyp18 chaperone activity was demonstrated. The induced correction of misfolded conformations by Cyp18 likely functions through rescue from misfolding of transient molten globule intermediates. ANS binding data suggest that the interaction by Cyp18 leads to an early stage condensation of accessible hydrophobic portions of the misfolding-prone protein substrate during folding. The opposite effect was observed for GroEL known as an unfoldase at early stages of refolding. The chaperone effect of Cyp18 was also demonstrated for citrate synthase, suggesting a general chaperone effect of this PPI.

  • 36.
    Moparthi, Satish Babu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    A nonessential role for Arg 55 in cyclophilin18 for catalysis of proline isomerization during protein folding2009In: Protein Science, ISSN 0961-8368, E-ISSN 1469-896X, Vol. 18, no 2, 475-479 p.Article in journal (Refereed)
    Abstract [en]

    The protein folding process is often in vitro rate-limited by slow cis-trans proline isomerization steps. Importantly, the rate of this process in vivo is accelerated by prolyl isomerases (PPIases). The archetypal PPIase is the human cyclophilin 18 (Cyp18 or CypA), and Arg 55 has been demonstrated to play a crucial role when studying short peptide substrates in the catalytic action of Cyp18 by stabilizing the transition state of isomerization. However, in this study we show that a R55A mutant of Cyp18 is as efficient as the wild type to accelerate the refolding reaction of human carbonic anhydrase II (HCA II). Thus, it is evident that the active-site located Arg 55 is not required for catalysis of the rate-limiting prolyl cis-trans isomerization steps during the folding of a protein substrate as HCA II. Nevertheless, catalysis of cis-trans proline isomerization in HCA II occurs in the active-site of Cyp18, since binding of the inhibitor cyclosporin A abolishes rate acceleration of the refolding reaction. Obviously, the catalytic mechanisms of Cyp18 can differ when acting upon a simple model peptide, four residues long, with easily accessible Pro residues compared with a large protein molecule undergoing folding with partly or completely buried Pro residues. In the latter case, the isomerization kinetics are significantly slower and simpler mechanistic factors such as desolvation and/or strain might operate during folding-assisted catalysis, since binding to the hydrophobic active site is still a prerequisite for catalysis.

  • 37.
    Moparthi, Satish Babu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Not merely a passive co-chaperone: dynamic remodeling of protein substrate by GroES alone and in concert with GroELManuscript (preprint) (Other academic)
    Abstract [en]

    Stopped‐flow folding experiments of human carbonic anhydrase II (HCA II) monitored by ANS fluorescence showed formation of an early molten globule intermediate. Folding of HCA II both in the presence of GroEL alone or GroES alone led to a loss of ANS binding compared to that in the spontaneous refolding process, showing that GroES alone is capable to interact with the refolding protein and that the molten globule substrate seems to be brought into a more unfolded state by both chaperonins. Moreover, an additive effect of the reduction of ANS binding during the early refolding stages was observed in the presence of GroEL+GroES, suggesting a concerted additive decrease in formation of molten globule by the chaperonins. The interactions during folding (from 50 ms to 3 h) between HCA II and GroEL alone, GroES alone, GroEL/ES and GroEL/ES/ATP was monitored in more detail using five fluorescence (AEDANS) labeled HCA II mutants and steady‐state and stopped‐flow Trp‐AEDANS FRET measurements. We observed that GroEL stretches the protein substrate as an early event in the folding process, when compared to spontaneous folding. Interestingly, GroES alone can interact with the folding protein leading to remodelling of the structure of the molten globule intermediate. Furthermore, GroES exerts additive stretching effects of the protein substrate in concert with GroEL. However, in the absence of GroEL the action by GroES is transient and does not affect the reactivation kinetics or final yield and thereby GroES does not exhibit classical chaperone activity, which is likely the reason why the independent GroES activity on protein substrates has gone undiscovered for such a long time.

  • 38.
    Mårtensson, Lars-Göran
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Karlsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Dramatic stabilization of the native state of human carbonic anhydrase II by an engineered disulfide bond2002In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 41, no 52, 15867-15875 p.Article in journal (Refereed)
    Abstract [en]

    To find a disulfide pair that could stabilize the enzyme human carbonic anhydrase II (HCA II), we grafted the disulfide bridge from the related and unusually stable carbonic anhydrase form from Neisseria gonorrhoeae (NGCA) into the human enzyme. Thus, the two Cys residues at positions 23 and 203 were engineered into a pseudo-wild-type form of HCA II (C206S), giving the mutant C206S/A23C/L203C. The disulfide bond was not formed spontaneously. The native state of the reduced form of the mutant was markedly destabilized (2.9 kcal/mol) compared to that of HCA II. Formation of a disulfide bridge was achieved by treatment by oxidized glutathione. This led to a significant stabilization of the native conformation. Compared to HCA II the unfolding midpoint for the variant was increased from 0.9 to 1.7 M guanidine HCl, corresponding to a stabilization of 3.7 kcal/mol. This makes the human enzyme almost as stable as the model protein NGCA, for which the unfolding of the native state has a midpoint at 2.1 M guanidine HCl. The stabilized protein underwent, contrary to all other investigated variants of HCA II, an apparent two-state unfolding transition, as judged from intrinsic Trp fluorescence measurements. A molten−globule intermediate is nevertheless formed but is suppressed because of the high denaturant pressure it faces upon rupture of the native state.

  • 39.
    Nayeri, Fariba
    et al.
    Linköping University, Department of Molecular and Clinical Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences.
    Xu, Junjang
    Linköping University, Department of Molecular and Clinical Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences.
    Abdiu, Avni
    Linköping University, Department of Biomedicine and Surgery, Plastic Surgery, Hand Surgery and Burns. Linköping University, Faculty of Health Sciences.
    Nayeri, Tayeb
    Linköping University, Department of Molecular and Clinical Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences.
    Aili, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Health Sciences.
    Autocrine production of biologically active hepatocyte growth factor (HGF) by injured human skin2006In: Journal of dermatological science (Amsterdam), ISSN 0923-1811, E-ISSN 1873-569X, Vol. 43, no 1, 49-56 p.Article in journal (Refereed)
    Abstract [en]

    Background

    Hepatocyte growth factor (HGF) is a potent regenerative factor involved in wound healing. Previous studies have shown that mesenchymal cells produce HGF, stimulating epithelial cells in a paracrine fashion.

    Objective

    To examine whether autocrine HGF production by keratinocytes can occur upon skin injury.

    Methods

    A 31-year-old male patient sustained a burn affecting 80% of his total body surface area. Biopsies were taken from intact skin near the injured area, and skin keratinocytes were separated and cultured. Conditioned medium from keratinocytes was analyzed for HGF by ELISA, surface plasmon resonance (SPR), and dot blotting. Binding of HGF from conditioned medium to its receptor, c-Met, was compared with recombinant HGF by SPR. Finally, we examined the motogenic effect on mouse transformed skin epithelial cells (CCL-53.1) of HGF from conditioned medium.

    Results

    HGF was detected in the cultured keratinocyte medium. Similar to recombinant HGF, HGF from conditioned medium had a high affinity for dextran sulfate and albumin, and the same epitopes were engaged by the interaction of HGF with the c-Met receptor. The conditioned medium from keratinocytes obtained from the burn patient, but not medium from keratinocytes obtained from healthy volunteers, accelerated the motogenesis of CCL-53.1 cells. Unexpectedly, anti-HGF antibodies did not prevent this effect. However, anti-c-Met antibodies completely inhibited the motogenic effect.

    Conclusion

    Upon injury, human skin keratinocytes might produce biologically active HGF in an autocrine fashion. This HGF might have different structural and/or biological properties from HGF produced by mesenchymal cells.

  • 40.
    Osterlund, Maria
    et al.
    Novo Nordisk AS, Prot Biotechnol, DK-2880 Bagsvaerd, Denmark Linkoping Univ, IFM, Dept Chem, Linkoping, Sweden Linkoping Univ, IFM, Dept Phys Chem, Linkoping, Sweden Novo Nordisk AS, Vasc Biochem, Malov, Denmark.
    Owenius, Rikard
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Carlsson, Karin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Persson, Egon
    Vascular Biochemistry, Novo Nordisk A/S, Denmark.
    Lindgren, Mikael
    Department of Laser Systems, Division of Sensor Technology, Swedish Defence Research Agency, P.O. Box 1165, SE- 581 11 Linko¨ping, Sweden..
    Freskgård, Per-Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Svensson, Magdalena
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Probing inhibitor-induced conformational changes along the interface between tissue factor and factor VIIa2001In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 40, no 31, 9324-9328 p.Article in journal (Refereed)
    Abstract [en]

    Upon injury of a blood vessel, activated factor VII (FVIIa) forms a high-affinity complex with its allosteric regulator, tissue factor (TF), and initiates blood clotting. Active site-inhibited factor VIIa (FVIIai) binds to TF with even higher affinity. We compared the interactions of FVIIai and FVIIa with soluble TF (sTF). Six residues in sTF were individually selected for mutagenesis and site-directed labeling. The residues are distributed along the extensive binding interface, and were chosen because they are known to interact with the different domains of FVIIa. Fluorescent and spin probes were attached to engineered Cys residues to monitor local changes in hydrophobicity, accessibility, and rigidity in the sTF-FVIIa complex upon occupation of the active site of FVIIa. The results show that inhibition of FVIIa caused the structures around the positions in sTF that interact with the protease domain of FVIIa to become more rigid and less accessible to solvent. Thus, the presence of an active site inhibitor renders the interface in this region less flexible and more compact, whereas the interface between sTF and the light chain of FVIIa is unaffected by active site occupancy.

  • 41.
    Osterlund, Marie
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Owenius, Rikard
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Persson, E.
    Tissue Factor/Factor VII Research, Novo Nordisk A/S, Måløv, Denmark.
    Lindgren, M.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Freskgard, P.-O.
    Freskgård, P.-O., Tissue Factor/Factor VII Research, Novo Nordisk A/S, Måløv, Denmark.
    Svensson, Magdalena
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Spectroscopic probing of the influence of calcium and the Gla domain on the interaction between the first EGF domain in factor VIla and tissue factor2000In: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 267, no 20, 6204-6211 p.Article in journal (Refereed)
    Abstract [en]

    The binding of factor VIIa (FVIIa) to tissue factor (TF) initiates blood coagulation. The binary complex is dependent on Ca2+ binding to several sites in FVIIa and is maintained by multiple contacts distributed throughout the various domains. Although the contributions from various residues and domains, including the Ca2+ coordination, to the global binding energy have been characterized, their importance for specific local interactions is virtually unknown. To address this aspect, we have attached four spectroscopic probes to an engineered Cys residue replacing Phe140 in soluble TF (sTF). This allows the monitoring of local changes in hydrophobicity and rigidity upon complex formation at the interface between the first epidermal growth factor-like (EGF1) domain of FVIIa and sTF. The fluorescent labels used sense a more hydrophobic environment and the spin labels are dramatically immobilized when FVIIa binds sTF. The results obtained with a 4-carboxy-glutamic acid (Gla)-domainless derivative of FVIIa indicate that the Gla domain has no or minimal influence on the interaction between EGF1 and sTF. However, there is a difference in local Ca2+ dependence between Gla-domainless and full-length FVIIa.

  • 42.
    Osterlund, Marie
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Owenius, Rikard
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Svensson, Magdalena
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Lindgren, M
    Persson, E
    Freskgård, Per-Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Mapping local interactions and resolving association kinetics for a receptor-ligand system2000Conference paper (Other academic)
  • 43.
    Owenius, Rikard
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Jarl, Anngelica
    Linköping University, Department of Physics, Chemistry and Biology, Molecular genetics. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Eaton, Sandra
    University of Denver, Department of Chemistry & Biochemistry Denver, USA.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    GroEL-induced stretching of a substrate protein: An EPR/SDSL study in BIOPHYSICAL JOURNAL, vol 88, issue 1, pp 562A-562A2005In: BIOPHYSICAL JOURNAL, Elsevier (Cell Press) / Biophysical Society , 2005, Vol. 88, no 1, 562A-562A p.Conference paper (Refereed)
    Abstract [en]

    The Hsp60-type chaperonin GroEL assists in the folding of the enzyme Human Carbonic Anhydrase II (HCA II) and protects it from aggregation.It is still a controversy whether the action of GroEL is an active or passive process. Single- and double-cysteine mutants were specificallyspin labeled at a topological breakpoint in the β-core of HCA II. X-band electron paramagnetic resonance (EPR) was used at physiologicaltemperatures to monitor the GroEL-induced structural changes in this region of HCA II. Inter-residue distance calculations based on dipolarinteraction show that the proximity of the labeled positions F147 and K213 in the native state of HCA II is ~11±2 Å, and that it is virtuallyintact in the thermally-induced molten-globule state that binds to GroEL. However, upon interaction with GroEL a spin-spin distance increaseto ~22±3 Å indicates a conformational change in HCA II that is part of the GroEL-induced substrate stretch that enables structural rearrangementof a misfolded substrate protein.

  • 44.
    Owenius, Rikard
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Chemical Physics .
    Jarl, Anngelica
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology .
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Jonsson, Bengt-Harald
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology .
    Hammarström, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    An unfolding machine in action: Streching by the chaperonin BroEL of the substrate protin core2006In: Cold Spring Harbor Molecular Chaperones and the heat shock response,2006, 2006Conference paper (Other academic)
  • 45.
    Owenius, Rikard
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Jarl, Anngelica
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology. Linköping University, The Institute of Technology.
    Jonsson, Bengt-Harald
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    GroEL-induced topological dislocation of a substrate protein β-sheet core: a solution EPR spin–spin distance study2010In: Journal of chemical biology, ISSN 1864-6158, E-ISSN 1864-6166, Vol. 3, no 3, 127-39 p.Article in journal (Refereed)
    Abstract [en]

    The Hsp60-type chaperonin GroEL assists in the folding of the enzyme human carbonic anhydrase II (HCA II) and protects it from aggregation. This study was aimed to monitor conformational rearrangement of the substrate protein during the initial GroEL capture (in the absence of ATP) of the thermally unfolded HCA II molten-globule. Single- and double-cysteine mutants were specifically spin-labeled at a topological breakpoint in the β-sheet rich core of HCA II, where the dominating antiparallel β-sheet is broken and β-strands 6 and 7 are parallel. Electron paramagnetic resonance (EPR) was used to monitor the GroEL-induced structural changes in this region of HCA II during thermal denaturation. Both qualitative analysis of the EPR spectra and refined inter-residue distance calculations based on magnetic dipolar interaction show that the spin-labeled positions F147C and K213C are in proximity in the native state of HCA II at 20 °C (as close as ∼8 Å), and that this local structure is virtually intact in the thermally induced molten-globule state that binds to GroEL. In the absence of GroEL, the molten globule of HCA II irreversibly aggregates. In contrast, a substantial increase in spin–spin distance (up to >20 Å) was observed within minutes, upon interaction with GroEL (at 50 and 60 °C), which demonstrates a GroEL-induced conformational change in HCA II. The GroEL binding-induced disentanglement of the substrate protein core at the topological break-point is likely a key event for rearrangement of this potent aggregation initiation site, and hence, this conformational change averts HCA II misfolding.

  • 46.
    Owenius, Rikard
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Osterlund, Marie
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Svensson, Magdalena
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Lindgren, M
    Persson, E
    Freskgård, Per-Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Spin and fluorescent probing of the binding interface between tissue factor and factor VIIa at multiple sites2001In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 81, no 4, 2357-2369 p.Article in journal (Refereed)
    Abstract [en]

    The specific complex between the extracellular part of tissue factor (sTF) and factor Vlla (FVlla) was chosen as a model for studies of the binding interface between two interacting proteins. Six surface-exposed positions in sTF, residues known to contribute to the sTF-FVlla interaction, were selected for cysteine mutation and site-directed labeling with spin and fluorescent probes. The binding interface was characterized by spectral data from electron paramagnetic resonance (EPR) and steady-state and time-domain fluorescence spectroscopy. The labels reported on compact local environments at positions 158 and 207 in the interface region between sTF and the gamma -carboxyglutamic acid (Gla) domain of FVlla, and at positions 22 and 140 in the interface region between sTF and the first epidermal growth factor-like (EGF1) domain of FVlla. The tightness of the local interactions in these parts of the interface is similar to that seen in the interior of globular proteins. This was further emphasized by the reduced local polarity detected by the fluorescent label upon FVlla binding, especially in the sTF-Gla region. There were indications of structural rigidity also at positions 45 and 94 in the interface region between sTF and the protease domain (PD) of FVlla, despite the perturbed cofactor function of these sTF variants. The results of the present study indicate that the multi-probing approach enables comparison of the tightness and characteristics of interaction along the binding interface of a protein complex. This approach also increases the probability of acquiring reliable structural data that are descriptive of the wild-type proteins.

  • 47. Persson, M
    et al.
    Zhou, A
    Mitri, R
    Hammarström, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Eaton, GR
    Eaton, SS
    Distance determination between deeply buried position in human carbon anhydrase II2000In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 78, no 1, 2255Pos- p.Conference paper (Other academic)
  • 48.
    Persson, Malin
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Hammarström, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Lindgren, M.
    Jonsson, Bengt-Harald
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology .
    Svensson, Magdalena
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    EPR Mapping of Interactions Between Spin-labeled Variants of Human Carbonic Anhydrase II and GroEL. Evidence for increased flexibility of the hydrophobic core by the interaction.1999In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 38, 432-441 p.Article in journal (Refereed)
  • 49.
    Persson, Malin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Harbridge, JR
    Univ Denver, Dept Chem & Biochem, Denver, CO 80208 USA Linkoping Univ, Dept Chem, IFM, SE-58183 Linkoping, Sweden.
    Hammarström, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Mitri, R
    Univ Denver, Dept Chem & Biochem, Denver, CO 80208 USA Linkoping Univ, Dept Chem, IFM, SE-58183 Linkoping, Sweden.
    Mårtensson, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Carlsson, Uno
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biochemistry.
    Eaton, GR
    Univ Denver, Dept Chem & Biochem, Denver, CO 80208 USA Linkoping Univ, Dept Chem, IFM, SE-58183 Linkoping, Sweden.
    Eaton, SS
    Univ Denver, Dept Chem & Biochem, Denver, CO 80208 USA Linkoping Univ, Dept Chem, IFM, SE-58183 Linkoping, Sweden.
    Comparison of electron paramagnetic resonance methods to determine distances between spin labels on human carbonic anhydrase II2001In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 80, no 6, 2886-2897 p.Article in journal (Refereed)
    Abstract [en]

    Four doubly spin-labeled variants of human carbonic anhydrase II and corresponding singly labeled variants were prepared by site-directed spin labeling. The distances between the spin labels were obtained from continuous-wave electron paramagnetic resonance spectra by analysis of the relative intensity of the half-field transition, Fourier deconvolution of line-shape broadening, and computer simulation of line-shape changes. Distances also were determined by four-pulse double electron-electron resonance. For each variant, at least two methods were applicable and reasonable agreement between methods was obtained. Distances ranged from 7 to 24 W. The doubly spin-labeled samples contained some singly labeled protein due to incomplete labeling. The sensitivity of each of the distance determination methods to the noninteracting component was compared.

  • 50.
    Svedhem, Sofia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Enander, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Karlsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Sjöbom, Hans
    Biacore AB, Uppsala, Sweden.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Löfås, Stefan
    Biacore AB, Uppsala, Sweden.
    Mårtensson, Lars-Göran
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Sjöstrand, Sven-Erik
    Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
    Svensson, Stefan
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Carlsson, Uno
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Subtle differences in dissociation rates of interactions between destabilized human carbonic anhydrase II mutants and immobilized benzenesulfonamide inhibitors probed by a surface plasmon resonance biosensor2001In: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 296, no 2, 188-196 p.Article in journal (Refereed)
    Abstract [en]

    The development of commercial biosensors based on surface plasmon resonance has made possible careful characterization of biomolecular interactions. Here, a set of destabilized human carbonic anhydrase II (HCA II) mutants was investigated with respect to their interaction kinetics with two different immobilized benzenesulfonamide inhibitors. Point mutations were located distantly from the active site, and the destabilization energies were up to 23 kJ/mol. The dissociation rate of wild-type HCA II, as determined from the binding to the inhibitor with higher affinity, was 0.019 s−1. For the mutants, dissociation rates were faster (0.022–0.025 s−1), and a correlation between faster dissociation and a high degree of destabilization was observed. We interpreted these results in terms of increased dynamics of the tertiary structures of the mutants. This interpretation was supported by entropy determinations, showing that the entropy of the native structure significantly increased upon destabilization of the protein molecule. Our findings demonstrate the applicability of modern biosensor technology in the study of subtle details in molecular interaction mechanisms, such as the long-range effect of point mutations on interaction kinetics.

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