2plx

From Proteopedia

Revision as of 10:56, 23 January 2008

Trypsin complexed to a synthetic peptide from Veronica hederifolia

Overview

The storage tissues of many plants contain protease inhibitors which are, believed to play an important role in defending the plant from invasion by, pests and pathogens. These proteinaceous inhibitor molecules belong to a, number of structurally distinct families. We describe here the isolation, purification, initial inhibitory properties and three dimensional, structure of a novel trypsin inhibitor from seeds of Veronica hederifolia, (VhTI). The VhTI peptide inhibits trypsin with a sub-micromolar apparent, Ki, and is expected to be specific for trypsin-like serine proteases. VhTI, differs dramatically in structure from all previously-described families, of trypsin inhibitors, consisting of a helix-turn-helix motif, with the, two alpha helices tightly associated by two disulphide bonds. Unusually, the crystallised complex is in the form of a stabilised acyl-enzyme, intermediate with the scissile bond of the VhTI inhibitor cleaved and the, resulting N-terminal portion of the inhibitor remaining attached to the, trypsin catalytic serine 195 by an ester bond. A synthetic, truncated, version of the VhTI peptide has also been produced and co-crystallised, with trypsin but, surprisingly, is seen to be uncleaved and consequently, forms a non-covalent complex with trypsin. The VhTI peptide shows that, effective enzyme inhibitors can be constructed from simple helical motifs, and provides a new scaffold on which to base the design of novel serine, protease inhibitors.

About this Structure

2PLX is a Single protein structure of sequence from Bos taurus with , and as ligands. Full crystallographic information is available from OCA.

Reference

An unusual helix-turn-helix protease inhibitory motif in a novel trypsin inhibitor from seeds of veronica (Veronica hederifolia L.)., Conners R, Konarev AV, Forsyth J, Lovegrove A, Marsh JT, Joseph-Horne T, Shewry P, Brady RL, J Biol Chem. 2007 Jul 19;. PMID:17640870

Page seeded by OCA on Wed Jan 23 12:56:57 2008