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Freskgård, Per-Ola
Publications (6 of 6) Show all publications
Andersson, D., Carlsson, U. & Freskgård, P.-O. (2001). Contribution of tryptophan residues to the CD spectrum of the extracellular domain of human tissue factor: Application in folding studies and prediction of secondary structure. European Journal of Biochemistry, 268(4), 1118-1128
Open this publication in new window or tab >>Contribution of tryptophan residues to the CD spectrum of the extracellular domain of human tissue factor: Application in folding studies and prediction of secondary structure
2001 (English)In: European Journal of Biochemistry, ISSN 0014-2956, E-ISSN 1432-1033, Vol. 268, no 4, p. 1118-1128Article in journal (Refereed) Published
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.

Keywords
Aromatic residues, Circular dichroism, Folding, Prediction, Secondary structure, Tissue factor
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-47393 (URN)10.1046/j.1432-1327.2001.01981.x (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
Osterlund, M., Owenius, R., Carlsson, K., Carlsson, U., Persson, E., Lindgren, M., . . . Svensson, M. (2001). Probing inhibitor-induced conformational changes along the interface between tissue factor and factor VIIa. Biochemistry, 40(31), 9324-9328
Open this publication in new window or tab >>Probing inhibitor-induced conformational changes along the interface between tissue factor and factor VIIa
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2001 (English)In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 40, no 31, p. 9324-9328Article in journal (Refereed) Published
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.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-49196 (URN)10.1021/bi010283n (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-12Bibliographically approved
Owenius, R., Osterlund, M., Svensson, M., Lindgren, M., Persson, E., Freskgård, P.-O. & Carlsson, U. (2001). Spin and fluorescent probing of the binding interface between tissue factor and factor VIIa at multiple sites. Biophysical Journal, 81(4), 2357-2369
Open this publication in new window or tab >>Spin and fluorescent probing of the binding interface between tissue factor and factor VIIa at multiple sites
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2001 (English)In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 81, no 4, p. 2357-2369Article in journal (Refereed) Published
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.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-48183 (URN)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-12
Carlsson, U., Hammarström, P., Lindgren, M., Persson, M., Freskgård, P.-O., Mårtensson, L.-G., . . . Svensson, M. (2000). 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.. Biophysical Journal, 78(1)
Open this publication in new window or tab >>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.
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2000 (English)In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 78, no 1, p. 202Pos-Conference paper, Published paper (Other academic)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-49870 (URN)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2018-04-25
Osterlund, M., Owenius, R., Svensson, M., Lindgren, M., Persson, E., Freskgård, P.-O. & Carlsson, U. (2000). Mapping local interactions and resolving association kinetics for a receptor-ligand system. , 78(1)
Open this publication in new window or tab >>Mapping local interactions and resolving association kinetics for a receptor-ligand system
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2000 (English)Conference paper, Published paper (Other academic)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-48369 (URN)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2012-02-17
Hammarström, P., Persson, M., Freskgård, P.-O., Mårtensson, L.-G., Andersson, D., Jonsson, B.-H. & Carlsson, U. (1999). Structural mapping of an aggregation nucleation site in a molten-globule intermediate. Journal of Biological Chemistry, 274, 32897-32903
Open this publication in new window or tab >>Structural mapping of an aggregation nucleation site in a molten-globule intermediate
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1999 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 274, p. 32897-32903Article in journal (Refereed) Published
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-42070 (URN)60197 (Local ID)60197 (Archive number)60197 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2018-04-25
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