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  • 1. Andersson, LK
    et al.
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Baltzer, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Multifunctional folded polypeptides from peptide synthesis and site-selective self-functionalization - Practical scaffolds in aqueous solution2002In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 3, no 8, p. 741-751Article in journal (Refereed)
    Abstract [en]

    The site selectivity of His-mediated lysine and ornithine side-chain acylation in a designed four-helix bundle protein scaffold was mapped by reaction of several polypeptides with one equivalent of mono-p-nitrophenyl fumarate in aqueous solution at pH 5.9 and room temperature followed by an analysis of the degrees and sites of acylation. Integration of the HPLC chromatograms of the acylated polypeptides and trypsin cleavage followed by mass spectrometry analysis of the tryptic fragments provided the experimental evidence. Based on these and previously published results a strategy was developed for the site-selective and stepwise incorporation of three residues into a folded polypeptide in aqueous solution at room temperature. The first substituent was incorporated by reaction of a 1.7-fold excess of the corresponding active ester with the polypeptide at pH 5.9, the second substituent was introduced in a 3-fold excess after the pH value was raised to 8, and the third substituent was incorporated by reaction of a 10-fold excess with the polypeptide at pH 5.9. No intermediate steps of purification were taken and the overall yield was 30% or more. Examples of the substituents included are carbohydrates, an enzyme inhibitor, a fumarate, and an acetate group. The introduction of different substituents into three individually addressable positions in a stepwise, efficient, and controllable reaction demonstrates that designed folded polypeptides are practically useful scaffolds that can be functionalized by using very simple chemistry in aqueous solution. Predicted applications include designed receptors, biosensors, and molecular devices.

  • 2. Andersson, LK
    et al.
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Kihlberg, J
    Baltzer, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    The effect of glycosylation on the structure of designed four-helix bundle motifs2000In: JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2, ISSN 0300-9580, no 3, p. 459-464Article in journal (Refereed)
    Abstract [en]

    A galactose-, 1, and a cellobiose derivative, 2, have been site selectively, post-translationally, incorporated into a folded helix-loop-helix dimer LA-42b in a one step reaction at room temperature. The structural effects on the folded peptide upon glycosylation have been studied by CD and NMR spectroscopy. The negative value of the mean residue ellipticity of the folded peptide, LA-42b, was raised from -19000 +/- 1000 to -21200 +/- 1000 deg cm(2) dmol(-1) upon introduction of the galactose derivative and to -19500 +/- 1000 deg cm(2) dmol(-1) upon introduction of the cellobiose derivative, showing that the helical content was increased. The dissociation constant of the dimer decreased from 120 to 30 mu M upon glycosylation. The introduction of 1 into GTD-C, a folded helix-loop-helix dimer with a well defined tertiary structure, had little structural impact. Glycosylation stabilises the folded structure of proteins with partially exposed hydrophobic cores but has little effect on well-packed proteins.

  • 3.
    Andersson, Theresa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lundqvist, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology . Linköping University, The Institute of Technology.
    Dolphin, Gunnar T.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Enander, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . 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.
    Nilsson, Jonas W.
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry . Linköping University, The Institute of Technology.
    Baltzer, Lars
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    The binding of human Carbonic Anhydrase II by functionalized folded polypeptide receptors2005In: Chemistry and Biology, ISSN 1074-5521, E-ISSN 1879-1301, Vol. 12, no 11, p. 1245-1252Article in journal (Refereed)
    Abstract [en]

    Several receptors for human carbonic anhydrase II (HCAII) have been prepared by covalently attaching benzenesulfonamide carboxylates via aliphatic aminocarboxylic acid spacers of variable length to the side chain of a lysine residue in a designed 42 residue helix-loop-helix motif. The sulfonamide group binds to the active site zinc ion of human carbonic anhydrase II located in a 15 Å deep cleft. The dissociation constants of the receptor-HCAII complexes were found to be in the range from low micromolar to better than 20 nM, with the lowest affinities found for spacers with less than five methylene groups and the highest affinity found for the spacer with seven methylene groups. The results suggest that the binding is a cooperative event in which both the sulfonamide residue and the helix-loop-helix motif contribute to the overall affinity.

  • 4.
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    A designed branched three-helix bundle protein dimer2006In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 128, no 22, p. 7287-7290Article in journal (Refereed)
    Abstract [en]

    The ultimate goals of de novo protein design are the construction of novel tertiary structures and functions. Here is presented the design and synthesis of a uniquely branched three-helix bundle that folds into a well-folded dimeric protein. The branching of this protein was performed by the method of native chemical ligation, which provides a chemoselective and stable amide bond between the unprotected fragments. This ligation strategy was possible by the presented facile preparation of a peptide (43 amino acids) with a specific side chain thioester, which is synthesized by general Fmoc solid phase peptide synthesis. From the presented structural analysis, it is seen that the folded protein is present as a stable and highly helical dimer, thus forming a six-helix bundle. This unique tertiary structure, composed of a dimer of three individual a-helices branched together, offers different possibilities for protein engineering, such as metal and cofactor binding sites, as well as for the construction of novel functions. © 2006 American Chemical Society.

  • 5.
    Enander, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Andersson, Linda
    Göteborg universitet.
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Baltzer, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Designed, folded polypeptides for bioanalytical purposes - molecular scaffolds that combine recognition and reporting2001In: 4th International Conference on Structural Molecular Biology,2001, 2001Conference paper (Other academic)
    Abstract [en]

      

  • 6.
    Enander, Karin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Dolphin, Gunnar
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Andersson, Linda
    Department of Organic Chemistry Göteborg University.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Baltzer, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Designed, folded polypeptide scaffolds that combine key biosensing events of recognition and reporting2002In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 67, no 9, p. 3120-3123Article in journal (Refereed)
    Abstract [en]

    No abstract available.

  • 7.
    Enander, Karin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Dolphin, Gunnar
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Baltzer, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Designed, functionalized helix-loop-helix motifs that bind human carbonic anhydrase II: a new class of synthetic receptor molecules2004In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 126, no 14, p. 4464-4465Article in journal (Refereed)
    Abstract [en]

    Polypeptides designed to fold into helix−loop−helix motifs and to dimerize to form four-helix bundles were functionalized by the introduction of a sulfonamide derivative known to bind human carbonic anhydrase II (HCAII) and one or both of the dansyl- and methoxycoumarin fluorescent probes. The 42-residue sequence DC that carries all three substituents in solvent-exposed positions was found to bind HCAII with a dissociation constant of 5 nM in aqueous solution at pH 7. At 2 μM concentration, DC was mainly dimeric in aqueous solution but bound HCAII as a monomer. Upon addition of a large excess of a helix−loop−helix motif without a high-affinity ligand, KE2-Q, a ternary complex was formed between HCAII, DC, and KE2-Q. Hydrophobic interactions between DC and HCAII and coordination of the sulfonamide group to the zinc ion of HCAII contributed cooperatively to binding in a demonstration of the usefulness of folded polypeptide−small organic molecule chimera as novel protein receptors. The DC homodimer was found to be a very sensitive biosensor component due to intermolecular quenching of its fluorescence that was inhibited upon binding to HCAII.

  • 8.
    Enander, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Baltzer, Lars
    Uppsala universitet.
    Structure-dependent signalling in fluorescent biosensor units based on designed, folded polypeptide scaffolds2004In: 19:e Organikerdagarna,2004, 2004Conference paper (Other academic)
    Abstract [en]

      

  • 9.
    Enander, Karin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Dolphin, Gunnar
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Baltzer, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    A versatile polypeptide platform for integrated recognition and reporting: affinity arrays for protein-ligand interaction analysis2004In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 10, no 10, p. 2375-2385Article in journal (Refereed)
    Abstract [en]

    A molecular platform for protein detection and quantification is reported in which recognition has been integrated with direct monitoring of target-protein binding. The platform is based on a versatile 42-residue helix–loop–helix polypeptide that dimerizes to form four-helix bundles and allows site-selective modification with recognition and reporter elements on the side chains of individually addressable lysine residues. The well-characterized interaction between the model target-protein carbonic anhydrase and its inhibitor benzenesulfonamide was used for a proof-of-concept demonstration. An affinity array was designed where benzenesulfonamide derivatives with aliphatic or oligoglycine spacers and a fluorescent dansyl reporter group were introduced into the scaffold. The affinities of the array members for human carbonic anhydrase II (HCAII) were determined by titration with the target protein and were found to be highly affected by the properties of the spacers (dissociation constant Kd=0.02–3 μM). The affinity of HCAII for acetazolamide (Kd=4 nM) was determined in a competition experiment with one of the benzenesulfonamide array members to address the possibility of screening substance libraries for new target-protein binders. Also, successful affinity discrimination between different carbonic anhydrase isozymes highlighted the possibility of performing future isoform-expression profiling. Our platform is predicted to become a flexible tool for a variety of biosensor and protein-microarray applications within biochemistry, diagnostics and pharmaceutical chemistry.

  • 10.
    Enander, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Baltzer, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    De novo designed helix-loop-helix polypeptides - a structure-function-based design strategy for microarray and biosensor applications2003In: 1st World Congress on Synthetic Receptors,2003, 2003Conference paper (Refereed)
  • 11.
    Enander, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Baltzer, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Designed, folded polypeptides as functional units in biosensor applications2002In: 18:e Organikerdagarna,2002, 2002Conference paper (Other academic)
  • 12.
    Enander, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Löfdahl, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Baltzer, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Designed, folded polypeptides as functional units in surface-based biosensors - versatile scaffolds connecting recognition and reporting2002In: Europtrode VI,2002, 2002Conference paper (Refereed)
  • 13.
    Enander, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Löfdahl, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Baltzer, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Helix-loop-helix polypeptides as scaffolds for designed biosensing surfaces2002In: 6th World Congress on Biosensors,2002, 2002Conference paper (Other academic)
  • 14.
    Haversen, L.
    et al.
    Univ Gothenburg, Dept Infect Med Clin Bacteriol, S-41346 Gothenburg, Sweden.
    Kondori, N.
    Univ Gothenburg, Dept Infect Med Clin Bacteriol, S-41346 Gothenburg, Sweden.
    Baltzer, Lars
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    A Hanson, L A
    Univ Gothenburg, Dept Clin Immunol, S-41346 Gothenburg, Sweden.
    Dolphin, Gunnar
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Duner, K.
    Univ Gothenburg, Dept Infect Med Clin Bacteriol, S-41346 Gothenburg, Sweden.
    Mattsby-Baltzer, I.
    Univ Gothenburg, Dept Infect Med Clin Bacteriol, S-41346 Gothenburg, Sweden.
    Structure-Microbicidal Activity Relationship of Synthetic Fragments Derived from the Antibacterial alpha-Helix of Human Lactoferrin2010In: Antimicrobial Agents and Chemotherapy, ISSN 0066-4804, E-ISSN 1098-6596, Vol. 54, no 1, p. 418-425Article in journal (Refereed)
    Abstract [en]

    There is a need for new microbicidal agents with therapeutic potential due to antibiotic resistance in bacteria and fungi. In this study, the structure-microbicidal activity relationship of amino acid residues 14 to 31 (sequence 14-31) from the N-terminal end, corresponding to the antibacterial alpha-helix of human lactoferrin (LF), was investigated by downsizing, alanine scanning, and substitution of amino acids. Microbicidal analysis (99% killing) was performed by a microplate assay using Escherichia coli, Staphylococcus aureus, and Candida albicans as test organisms. Starting from the N-terminal end, downsizing of peptide sequence 14-31 showed that the peptide sequence 19-31 (KCFQWQRNMRKVR, HL9) was the optimal length for antimicrobial activity. Furthermore, HL9 bound to lipid A/lipopolysaccharide, as shown by neutralizing endotoxic activity in a Limulus assay. Alanine scanning of peptide sequence 20-31 showed that Cys20, Trp23, Arg28, Lys29, or Arg31 was important for expressing full killing activity, particularly against C. albicans. Substituting the neutral hydrophilic amino acids Gln24 and Asn26 for Lys and Ala (HLopt2), respectively, enhanced microbicidal activity significantly against all test organisms compared to the amino acids natural counterpart, also, in comparison with HL9, HLopt2 had more than 10-fold-stronger fungicidal activity. Furthermore, HLopt2 was less affected by metallic salts than HL9. The microbicidal activity of HLopt2 was slightly reduced only at pH 7.0, as tested in the pH range of 4.5 to 7.5. The results showed that the microbicidal activity of synthetic peptide sequences, based on the antimicrobial alpha-helix region of LF, can be significantly enhanced by optimizing the length and substitution of neutral amino acids at specific positions, thus suggesting a sequence lead with therapeutic potential.

  • 15.
    Kondori, N
    et al.
    Gothenburg University.
    Baltzer, Lars
    Uppsala University.
    Dolphin, Gunnar
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Mattsby-Baltzer, I
    Gothenburg University.
    Fungicidal activity of human lactoferrin-derived peptides based on the antimicrobial alpha beta region2011In: INTERNATIONAL JOURNAL OF ANTIMICROBIAL AGENTS, ISSN 0924-8579, Vol. 37, no 1, p. 51-57Article in journal (Refereed)
    Abstract [en]

    Owing to the increasing number of infections in hospitalised patients caused by resistant strains of fungi, there is a need to develop new therapeutic agents for these infections. Naturally occurring antimicrobial peptides may constitute models for developing such agents. A modified peptide sequence (CFQWKRAM-RKVR; HLopt2) based on amino acid residues 20-31 of the N-terminal end of human lactoferrin (hLF) as well as a double-sized human lactoferricin-like peptide (amino acid residues 16-40; HLBD1) were investigated for their antifungal activities in vitro and in vivo. By in vitro assay, HLopt2 was fungicidal at concentrations of 12.5-25 mu g/mL against Cryptococcus neoformans, Candida albicans, Candida krusei, Candida kefyr and Candida parapsilosis, but not against Candida glabrata. HLopt2 was demonstrated to have andgt;= 16-fold greater killing activity than HLBD1. By inducing some helical formation caused by lactam bridges or by extending the assay time (from 2 h to 20 h), HLBD1 became almost comparable with HLopt2 in its fungicidal activity. Killing of C. albicans yeast cells by HLopt2 was rapid and was accompanied by cytoplasmic and mitochondrial membrane permeabilisation as well as formation of deep pits on the yeast cell surface. In a murine C. albicans skin infection model, atopic treatment with the peptides resulted in significantly reduced yields of Candida from the infected skin areas. The antifungal activities of HLopt2 in vitro and in vivo suggest possible potential as a therapeutic agent against most Candida spp. and C. neoformans. The greatly improved antifungal effect of the lactam-modified HLBD1 indicates the importance of amphipathic helix formation for lethal activity.

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