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PDBsum entry 1gec
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Hydrolase/hydrolase inhibitor
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PDB id
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1gec
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Crystal structure of glycyl endopeptidase from carica papaya: a cysteine endopeptidase of unusual substrate specificity.
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Authors
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B.P.O'Hara,
A.M.Hemmings,
D.J.Buttle,
L.H.Pearl.
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Ref.
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Biochemistry, 1995,
34,
13190-13195.
[DOI no: ]
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PubMed id
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Note In the PDB file this reference is
annotated as "TO BE PUBLISHED".
The citation details given above were identified by an automated
search of PubMed on title and author
names, giving a
perfect match.
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Abstract
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Glycyl endopeptidase is a cysteine endopeptidase of the papain family,
characterized by specificity for cleavage C-terminal to glycyl residues only and
by resistance to inhibition by members of the cystatin family of cysteine
proteinase inhibitors. Glycyl endopeptidase has been crystallized from high salt
with a substrate-like inhibitor covalently bound to the catalytic Cys 25. The
structure has been solved by molecular replacement with the structure of papain
and refined at 2.1 A to an R factor of 0.196 (Rfree = 0.258) with good geometry.
The structure of the S1 substrate binding site of glycyl endopeptidase differs
from that of papain by the substitution of glycines at residues 23 and 65 in
papain, with glutamic acid and arginine, respectively, in glycyl endopeptidase.
The side chains of these residues form a barrier across the binding pocket,
effectively excluding substrate residues with large side chains from the S1
subsite. The constriction of this subsite in glycyl endopeptidase explains the
unique specificity of this enzyme for cleavage after glycyl residues and is a
major component of its resistance to inhibition by cystatins.
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