PDBsum entry: 1sgc

Hydrolase/hydrolase inhibitor

PDB id: 1sgc

Contents

Protein chain

181 a.a. *

Ligands

PHE-CSI-LEU-PHA

Waters ×217

* Residue conservation analysis

PDB id:

1sgc

Name:

Hydrolase/hydrolase inhibitor

Title:

The 1.8 angstroms structure of the complex between chymostat streptomyces griseus protease a. A model for serine proteas catalytic tetrahedral intermediates

Structure:

Proteinase a. Chain: a. Engineered: yes. Chymostatin a. Chain: b. Engineered: yes

Source:

Streptomyces griseus. Organism_taxid: 1911. Synthetic: yes

Resolution:

1.80Å R-factor: 0.123

Authors:

L.T.J.Delbaere,G.D.Brayer

Key ref:

L.T.Delbaere and G.D.Brayer (1985). The 1.8 A structure of the complex between chymostatin and Streptomyces griseus protease A. A model for serine protease catalytic tetrahedral intermediates. J Mol Biol, 183, 89. PubMed id: 3892018 DOI: 10.1016/0022-2836(85)90283-9

Date:

18-Apr-86 Release date: 14-Jul-86

Protein chain

P00776  (PRTA_STRGR) -  Streptogrisin-A

Seq: 297 a.a.

Struc: 181 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.3.4.21.80 - Streptogrisin A.
• Reaction: Hydrolysis of proteins with specificity similar to chymotrypsin.

 Gene Ontology (GO) functional annotation 

• Biological process: proteolysis (1 term)
• Biochemical function: catalytic activity (2 terms)

DOI no: 10.1016/0022-2836(85)90283-9

J Mol Biol 183:89 (1985)

PubMed id: 3892018

The 1.8 A structure of the complex between chymostatin and Streptomyces griseus protease A. A model for serine protease catalytic tetrahedral intermediates.

L.T.Delbaere, G.D.Brayer.

ABSTRACT

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.

Selected figure(s)

Figure 3.
Figure 3. Variation in the conventional factor as a function of data shells with the indcated minimum d spacings.

Figure 11.
Figure 11. Stereo-drawing of the hemiacetal complex formed by the synthetic peptide aldehyde inhibitor in he active site of SGPA with the native enzyme is57 position illustrated. The actual is57 side-chain position inthis complex is given in Fig. 10(c). Steric conflict between the newly formed hemiacetal group and His57 appears to e responsible for the expulsion of the side-chain of this residue into surrounding solvent upon formation of the hemiacetal product.

The above figures are reprinted by permission from Elsevier: J Mol Biol (1985, 183, 89-0) copyright 1985.

Figures were selected by an automated process.