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PDBsum entry 1gci
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Serine protease
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PDB id
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1gci
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References listed in PDB file
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Key reference
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Title
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The 0.78 a structure of a serine protease: bacillus lentus subtilisin.
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Authors
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P.Kuhn,
M.Knapp,
S.M.Soltis,
G.Ganshaw,
M.Thoene,
R.Bott.
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Ref.
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Biochemistry, 1998,
37,
13446-13452.
[DOI no: ]
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PubMed id
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Abstract
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Ultrahigh-resolution X-ray diffraction data from cryo-cooled, B. lentus
subtilisin crystals has been collected to a resolution of 0.78 A. The refined
model coordinates have a rms deviation of 0.22 A relative to the same structure
determined at room temperature and 2.0 A resolution. Several regions of
main-chain and side-chain disorder have been identified for 21 out of 269
residues in one polypeptide chain. Hydrogen atoms appear as significant peaks in
the Fo - Fc difference electron density map, and carbon, nitrogen, and oxygen
atoms can be differentiated. The estimated standard deviation (ESD) for all
main-chain non-hydrogen bond lengths is 0.009 A and 0.5 degrees for bond angles
based on an unrestrained full-matrix least-squares refinement. Hydrogen bonds
are resolved in the serine protease catalytic triad (Ser-His-Asp). Electron
density is observed for an unusual, short hydrogen bond between aspartic acid
and histidine in the catalytic triad. The hydrogen atom, identified by NMR in
numerous serine proteases, appears to be shared by the heteroatoms in the bond.
This represents the first reported correlation between detailed chemical
features identified by NMR and those in a cryo-cooled crystallographic structure
determination at ultrahigh resolution. The short hydrogen bond, designated
"catalytic hydrogen bond", occurs as part of an elaborate hydrogen bond network,
involving Asp of the catalytic triad. While unusual, these features appear to
have conserved analogues in other serine protease families although specific
details differ from family to family.
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