title: Serine protease inhibition by insect peptides containing a cysteine knot and a triple-stranded beta-sheet.
abstract: Three insect peptides showing high sequence similarity and belonging to the same structural family incorporating a cysteine knot and a short three-stranded antiparalled beta-sheet were studied. Their inhibitory effect on two serine proteases (bovine alpha-chymotrypsin and human leukocyte elastase) is reported. One of them, PMP-C, is a strong alpha-chymotrypsin inhibitor (Ki = 0.2 nM) and interacts with leukocyte elastase with a Ki of 0.12 microM. The other two peptides, PMP-D2 and HI, interact only weakly with alpha-chymotrypsin and do not inhibit leukocyte elastase. Synthetic variants of these peptides were prepared by solid-phase synthesis, and their action toward serine proteases was evaluated. This enabled us to locate the P1 residues within the reactive sites (Leu-30 for PMP-C and Arg-29 for PMP-D2 and HI), and, interestingly, variants of PMP-D2 and HI were converted into powerful inhibitors of both alpha-chymotrypsin and leukocyte elastase, the most potent elastase inhibitor obtained in this study having a Ki of 3 nM.
authors.affiliation: Laboratoire de Chimie Organique des Substances Naturelles, Université Louis Pasteur, URA 31 CNRS, Strasbourg, France.
authors.forename: C
authors.initials: C
authors.lastname: Kellenberger
authors.forename: C
authors.initials: C
authors.lastname: Boudier
authors.forename: I
authors.initials: I
authors.lastname: Bermudez
authors.forename: J G
authors.initials: JG
authors.lastname: Bieth
authors.forename: B
authors.initials: B
authors.lastname: Luu
authors.forename: H
authors.initials: H
authors.lastname: Hietter
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002918:Chymotrypsin / Q000187:drug effects; D047169:Cyclotides; D004305:Dose-Response Relationship, Drug; D006020:Glycopeptides / Q000494:pharmacology; D006110:Grasshoppers / Q000737:chemistry*; D006458:Hemolymph / Q000737:chemistry; D006801:Humans; D007301:Insect Hormones / Q000494:pharmacology; D019476:Insect Proteins; D019272:Leukocyte Elastase; D008969:Molecular Sequence Data; D010196:Pancreatic Elastase / Q000187:drug effects; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D017433:Protein Structure, Secondary; D012697:Serine Endopeptidases / Q000187:drug effects*; D015842:Serine Proteinase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D047169:Cyclotides; D006020:Glycopeptides; C096379:HI peptide; D007301:Insect Hormones; D019476:Insect Proteins; D010455:Peptides; D015842:Serine Proteinase Inhibitors; C072986:PMP-D2 peptide, insect; C072987:PMP-C peptide, insect; D012697:Serine Endopeptidases; D002918:Chymotrypsin; D010196:Pancreatic Elastase; D019272:Leukocyte Elastase