Analysis of binding interactions of pepsin inhibitor-3 to mammalian and malarial aspartic proteases.

ABSTRACT: The nematode Ascaris suum primarily infects pigs, but also causes disease in humans. As part of its survival mechanism in the intestinal tract of the host, the worm produces a number of protease inhibitors, including pepsin inhibitor-3 (PI3), a 17 kDa protein. Recombinant PI3 expressed in E. coli has previously been shown to be a competitive inhibitor of a subgroup of aspartic proteinases: pepsin, gastricsin and cathepsin E. The previously determined crystal structure of the complex of PI3 with porcine pepsin (p. pepsin) showed that there are two regions of contact between PI3 and the enzyme. The first three N-terminal residues (QFL) bind into the prime side of the active site cleft and a polyproline helix (139-143) in the C-terminal domain of PI3 packs against residues 289-295 that form a

SUBMITTER: Moose RE 

PROVIDER: S-EPMC2518667 | biostudies-literature | 2007 Dec

REPOSITORIES: biostudies-literature