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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1gns

E.C. namesubtilisin
SpeciesBacillus amyloliquefaciens (strain FZB42)
E.C. Number (IntEnz) 3.4.21.62
CSA Homologues of 1gns
CSA Entries With UniProtID P00782
CSA Entries With EC Number 3.4.21.62
PDBe Entry 1gns
PDBSum Entry 1gns
MACiE Entry 1gns

Literature Report

IntroductionSubtilisin BPN' is an extracellular enzyme secreted by Bacillus amyloliquefaciens and belongs to the alpha/beta subtilase family. It is a serine-class endoprotease, hydrolysing peptide bonds with broad specificity and a preference for a large uncharged residue in the P1 binding site.
Mechansim1: His 64 acts as a general base, deprotonating Ser 221. Ser 221 performs nucleophilic attack on the carbonyl carbon of the amide bond. 2: This results in a tetrahedral transition state, which is stabilised through Coulombic interactions with protonated His 64, hydrogen bonding with the backbone amide of Ser 221 and the amide side-chain of Asn 155. The transition state is also stabilised by hydrogen bonding between the P1 amide nitrogen and the carbonyl oxygen of Ser 125. His 64 is stabilised by electrostatic interactions with Asp 32. 3: The tetrahedral transition state collapses, forming an acyl-enzyme and His 64 acts as a general acid, protonating the amide leaving group. 4: His 64 acts as a general base, deprotonating a water molecule. The activated water molecule performs nucleophilic attack upon the acyl enzyme, forming a tetrahedral transition state. 5: The tetrahedral transition state collapses, forming the acid component of the substrate and Ser 221. His 64 acts as a general acid, protonating the leaving group Ser 221.
Reaction

Catalytic Sites for 1gns

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
AsnA155262macie:sideChainThe amide side-chain of Asn 155 stabilises the first tetrahedral transition state through hydrogen bonding.
CsoA221328macie:ptmSer 221 is deprotonated by His 64 and performs nucleophilic attack on the carbonyl carbon of the amide bond, resulting in a tetrahedral transition state. The backbone amide group of Ser 221 hydrogen bonds with the tetrahedral transition state, stabilising it.
CsoA221328macie:mainChainAmideSer 221 is deprotonated by His 64 and performs nucleophilic attack on the carbonyl carbon of the amide bond, resulting in a tetrahedral transition state. The backbone amide group of Ser 221 hydrogen bonds with the tetrahedral transition state, stabilising it.
HisA64171macie:sideChain1: His 64 acts as a general base, deprotonating Ser 221. 2: Protonated His 64 stabilises the tetrahedral transition state through Coulombic interactions. 3: Protonated His 64 acts as a general acid, protonating the amide leaving group. 4: His 64 acts as a general base, deprotonating a water molecule. 5: Protonated His 64 acts as a general acid, protonating the leaving group Ser 221.
AspA32139macie:sideChainAsp 32 stabilises the positive charge on His 64 through electrostatic interactions.

Literature References

Notes:
Takeuchi Y
Refined crystal structure of the complex of subtilisin BPN' and Streptomyces subtilisin inhibitor at 1.8 A resolution.
J Mol Biol 1991 221 309-325
PubMed: 1920411
Bryan P
Site-directed mutagenesis and the role of the oxyanion hole in subtilisin.
Proc Natl Acad Sci U S A 1986 83 3743-3745
PubMed: 3520553
Carter P
Functional interaction among catalytic residues in subtilisin BPN'.
Proteins 1990 7 335-342
PubMed: 2199971
Blow DM
Role of a buried acid group in the mechanism of action of chymotrypsin.
Nature 1969 221 337-340
PubMed: 5764436
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