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

1995; Elsevier BV; Volume: 270; Issue: 43 Linguagem: Inglês

10.1074/jbc.270.43.25514

1083-351X

Christine Kellenberger, Christian Boudier, Isabel Bermúdez, Joseph G. Bieth, Bang Luu, Hélène Hietter,

Protein Hydrolysis and Bioactive Peptides

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. 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.