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Kellenberger, C ; Ferrat, G ; Leone, P ; Darbon, H ; Roussel, A

Selective inhibition of trypsins by insect peptides : Role of P6-P10 loop

Biochemistry 42 (46) 13605-13612

par Administrateur - publié le

Abstract :

PMP-D2 and HI, two peptides from Locusta migratoria, were shown to belong to the family of tight-binding protease inhibitors. However, they interact weakly with bovine trypsin (K-i around 100 nM) despite a trypsin-specific Arg at the primary specificity site P1. Here we demonstrate that they are potent inhibitors of midgut trypsins isolated from the same insect and of a fungal trypsin from Fusarium oxysporum (K-i less than or equal to 0.02 nM). Therefore, they display a selectivity not existing for the parent chymotrypsin inhibitor PMP-C. By NMR, we demonstrate that HI possesses a highly rigid structure similar to the crystal structure of a variant of PMP-D2 in complex with bovine a-chymotrypsin.