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PDBsum entry 4cms
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Hydrolase (acid proteinase)
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PDB id
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4cms
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References listed in PDB file
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Key reference
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Title
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X-Ray analyses of aspartic proteinases. Iv. Structure and refinement at 2.2 a resolution of bovine chymosin.
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Authors
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M.Newman,
M.Safro,
C.Frazao,
G.Khan,
A.Zdanov,
I.J.Tickle,
T.L.Blundell,
N.Andreeva.
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Ref.
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J Mol Biol, 1991,
221,
1295-1309.
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PubMed id
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Abstract
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The structure of calf chymosin (EC 3.4.23.3), the aspartic proteinase from the
gastric mucosa, was solved using the technique of molecular replacement. We
describe the use of different search models based on distantly related fungal
aspartic proteinases and investigate the effect of using only structurally
conserved regions. The structure has been refined to a crystallographic R-factor
of 17% at 2.2 A resolution with an estimated co-ordinate error of 0.21 A. In
all, 136 water molecules have been located of which eight are internal. The
structure of chymosin resembles that of pepsin and other aspartic proteinases.
However, there is a considerable rearrangement of the active-site "flap" and, in
particular, Tyr75 (pepsin numbering), which forms part of the specificity
pockets S1 and S1'. This is probably a consequence of crystal packing.
Electrostatic interactions on the edge of the substrate binding cleft appear to
account for the restricted proteolysis of the natural substrate kappa-casein by
chymosin. The local environment of invariant residues is examined, showing that
structural constraints and side-chain hydrogen bonding can play an important
role in the conservation of particular amino acids.
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Secondary reference #1
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Title
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Engineering enzyme subsite specificity: preparation, Kinetic characterization, And X-Ray analysis at 2.0-A resolution of val111phe site-Mutated calf chymosin.
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Authors
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P.Strop,
J.Sedlacek,
J.Stys,
Z.Kaderabkova,
I.Blaha,
L.Pavlickova,
J.Pohl,
M.Fabry,
V.Kostka,
M.Newman.
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Ref.
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Biochemistry, 1990,
29,
9863-9871.
[DOI no: ]
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PubMed id
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