Serine Protease Inhibition by Insect Peptides Containing a Cysteine Knot and a Triple-stranded β-Sheet (∗)

• Published in: The Journal of biological chemistry Vol. 270; no. 43; pp. 25514 - 25519
• Main Authors: Kellenberger, Christine, Boudier, Christian, Bermudez, Isabel, Bieth, Joseph G., Luu, Bang, Hietter, Hélène
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 27.10.1995
• Subjects: Amino Acid Sequence; Animals; BOVIN; Cattle; Chymotrypsin - drug effects; CHYMOTRYPSINE; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; Cyclotides; Dose-Response Relationship, Drug; GANADO BOVINO; GENERO HUMANO; GENRE HUMAIN; Glycopeptides - pharmacology; Grasshoppers - chemistry; Hemolymph - chemistry; Humans; INHIBICION; INHIBIDORES DE ENZIMAS; INHIBITEUR D'ENZYME; INHIBITION; Insect Hormones - pharmacology; Insect Proteins; Insecta; Leukocyte Elastase; LOCUSTA MIGRATORIA; Molecular Sequence Data; Pancreatic Elastase - drug effects; PEPTIDE; Peptides - chemistry; Peptides - pharmacology; PEPTIDOS; PROTEASAS; PROTEASE; Protein Structure, Secondary; QUIMOTRIPSINA; Serine Endopeptidases - drug effects; Serine Proteinase Inhibitors - chemistry; Serine Proteinase Inhibitors - pharmacology; Structure-Activity Relationship; TRIPSINA; TRYPSINE
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.43.25514

Three insect peptides showing high sequence similarity and belonging to the same structural family incorporating a cysteine knot and a short three-stranded antiparallel β-sheet were studied. Their inhibitory effect on two serine proteases (bovine α-chymotrypsin and human leukocyte elastase) is reported. One of them, PMP-C, is a strong α-chymotrypsin inhibitor (Ki = 0.2 nM) and interacts with leukocyte elastase with a Ki of 0.12 μM. The other two peptides, PMP-D2 and HI, interact only weakly with α-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 α-chymotrypsin and leukocyte elastase, the most potent elastase inhibitor obtained in this study having a Ki of 3 nM.