1sgc | pdb_00001sgc
|
THE 1.8 ANGSTROMS STRUCTURE OF THE COMPLEX BETWEEN CHYMOSTATIN AND STREPTOMYCES GRISEUS PROTEASE A. A MODEL FOR SERINE PROTEASE CATALYTIC TETRAHEDRAL INTERMEDIATES
Overview
The naturally occurring serine protease inhibitor, chymostatin, forms a, hemiacetal adduct with the catalytic Ser195 residue of Streptomyces, griseus protease A. Restrained parameter least-squares refinement of this, complex to 1.8 A resolution has produced an R index of 0 X 123 for the, 11,755 observed reflections. The refined distance of the carbonyl carbon, atom of the aldehyde to O gamma of Ser195 is 1 X 62 A. Both the R and S, configurations of the hemiacetal occur in equal populations, with the end, result resembling the expected configuration for a covalent tetrahedral, product intermediate of a true substrate. This study strengthens the, concept that serine proteases stabilize a covalent, tetrahedrally, co-ordinated species and elaborates those features of the enzyme, responsible for this effect. We propose that a major driving force for the, hydrolysis of peptide bonds by serine proteases is the non-planar, distortion of the scissile bond by the enzyme, which thereby lowers the, activation energy barrier to hydrolysis by eliminating the resonance, stabilization energy of the peptide bond.
About this Structure
1SGC is a Single protein structure of sequence from Streptomyces chryseus with CST as ligand. Full crystallographic information is available from OCA.
Reference
The 1.8 A structure of the complex between chymostatin and Streptomyces griseus protease A. A model for serine protease catalytic tetrahedral intermediates., Delbaere LT, Brayer GD, J Mol Biol. 1985 May 5;183(1):89-103. PMID:3892018
Page seeded by OCA on Wed Nov 21 02:21:55 2007
