1sgt

From Proteopedia

Revision as of 00:15, 21 November 2007

REFINED CRYSTAL STRUCTURE OF STREPTOMYCES GRISEUS TRYPSIN AT 1.7 ANGSTROMS RESOLUTION

Overview

Streptomyces griseus trypsin (SGT) is a bacterial serine proteinase that, is more homologous to mammalian than to other bacterial enzymes. The, structure of SGT has been solved primarily by molecular replacement, though some low-resolution phase information was supplied by heavy-atom, derivatives. The mammalian pancreatic serine proteinases bovine trypsin, (BT) and alpha-chymotrypsin (CHT) were used as molecular replacement, models. Because these proteins have low homology with SGT compared to the, majority of other successful replacement models, new strategies were, required for molecular replacement to succeed. The model of SGT has been, refined at 1.7 A resolution to a final R-factor of 0.161 (1 A = 0.1 nm);, the correlation coefficient between all observed and calculated structure, factor amplitudes is 0.908. Solvent molecules located in the crystal, structure play an important role in stabilizing buried charged and polar, groups. An additional contribution to stability can be seen in the fact, that the majority of the charged side-chains are involved in ionic, interactions, sometimes linking the two domains of SGT. A comparison of, SGT with BT shows that the greatest similarities are in the active-site, and substrate-binding regions, consistent with their similar substrate, specificities. The modeling of complexes of SGT with two inhibitors of BT, pancreatic trypsin inhibitor (PTI) and the third domain of Japanese quail, ovomucoid (OMJPQ3), helps to explain why PTI inhibits SGT but OMJPQ3 does, not. Like BT, but unlike other bacterial serine proteinases of known, structure, SGT has a buried N terminus. SGT has also a well-defined, Ca2+-binding site, but this site differs in location from that of BT.

About this Structure

1SGT is a Single protein structure of sequence from Streptomyces chryseus with CA as ligand. Active as Trypsin, with EC number 3.4.21.4 Full crystallographic information is available from OCA.

Reference

Refined crystal structure of Streptomyces griseus trypsin at 1.7 A resolution., Read RJ, James MN, J Mol Biol. 1988 Apr 5;200(3):523-51. PMID:3135412

Page seeded by OCA on Wed Nov 21 02:22:45 2007