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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1ds2

E.C. namestreptogrisin B
SpeciesStreptomyces griseus (strain JCM 4626 / NBRC 13350)
E.C. Number (IntEnz) 3.4.21.81
CSA Homologues of 1ds2There are 1160 Homologs
CSA Entries With UniProtID P00777
CSA Entries With EC Number 3.4.21.81
PDBe Entry 1ds2
PDBSum Entry 1ds2
MACiE Entry 1ds2

Literature Report

IntroductionSerine protease B extracted from Streptomyces griseus shows similar active site architecture to the well characterised family of human serine proteases and displays trypsin like specificity for its peptide substrates. It has proved especially useful in analysing the effect of peptide inhibitors such as turkey ovomucoid inhibitor.
MechansimSer 195 acts as the nucleophile to attack the peptide, forming the oxyanion intermediate, stabilised by hydrogen bonding to the oxyanion hole. Protonation of the leaving group by His 57 results in the collapse of the tetrahedral intermediate and the resulting acyl enzyme intermediate is hydrolysed by an activated water molecule to give the products.
Reaction

Catalytic Sites for 1ds2

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
AspE102177macie:sideChainForms hydrogen bond to His 57 to alter pKa suitably to facilitate its function as a general acid-base.
SerE195255macie:sideChainActs as nucleophile to attack the electrophilic carbon centre of the peptide substrate to form the tetrahedral intermediate. Stabilises the intermediate by hydrogen bonding from NH group. Subsequent collapse of the tetrahedral intermediate forms a covalent acyl-enzyme intermediate which can be hydrolysed to release the products.
SerE195255macie:mainChainAmideActs as nucleophile to attack the electrophilic carbon centre of the peptide substrate to form the tetrahedral intermediate. Stabilises the intermediate by hydrogen bonding from NH group. Subsequent collapse of the tetrahedral intermediate forms a covalent acyl-enzyme intermediate which can be hydrolysed to release the products.
GlyE193253macie:mainChainAmideForms hydrogen bond to stabilise tetrahedral intermediate via oxyanion hole.
HisE57147macie:sideChainActs to increase nucleophilicity of Ser 195 to allow formation of the tetrahedral intermediate. Protonates leaving group to facilitate collapse of the intermediate. Activates water to allow hydrolysis of the acyl-enzyme intermediate.

Literature References

Notes:
James MN
Crystal structure studies and inhibition kinetics of tripeptide chloromethyl ketone inhibitors with Streptomyces griseus protease B.
J Mol Biol 1980 139 423-438
PubMed: 6777499
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