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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1s2k

E.C. namescytalidopepsin B
SpeciesScytalidium lignicolum ()
E.C. Number (IntEnz) 3.4.23.32
CSA Homologues of 1s2k1s2b,1y43,2ifr,2ifw,
CSA Entries With UniProtID P15369
CSA Entries With EC Number 3.4.23.32
PDBe Entry 1s2k
PDBSum Entry 1s2k
MACiE Entry 1s2k

Literature Report

IntroductionScytalidopepsin-B is a member of a group of fungal pepstatin-insensitive glutamic peptidases known as the eqolsins. The enzyme has been shown to cleave angiotensin II and the oxidised insulin B chain, and operates most efficiently in acidic conditions. The eqolsins show no sequence homology to the well known pepsin-like or retroviral aspartic peptidases.
MechansimGlu 136 removes a proton from a water molecule which acts as a nucleophile to attack the peptide carbonyl. The tetrahedral intermediate and transition state leading to it is stabilised by hydrogen bonding from the side chain amide of Gln 53. Collapse of the intermediate with protonation of the departing nitrogen by Glu 136 completes the reaction.
Reaction

Catalytic Sites for 1s2k

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
GluA136190macie:sideChainRemoves a proton from a water molecule which then attacks the peptide carbonyl. Later protonates the departing amine leaving group.
GlnA53107macie:sideChainStabilises the tetrahedral intermediate/transition state.

Literature References

Notes:
Kataoka Y
Catalytic residues and substrate specificity of scytalidoglutamic peptidase, the first member of the eqolisin in family (G1) of peptidases.
FEBS Lett 2005 579 2991-2994
PubMed: 15907842
Fujinaga M
The molecular structure and catalytic mechanism of a novel carboxyl peptidase from Scytalidium lignicolum.
Proc Natl Acad Sci U S A 2004 101 3364-3369
PubMed: 14993599
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