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PDBsum entry 8ca2
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Lyase(oxo-acid)
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PDB id
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8ca2
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References listed in PDB file
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Key reference
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Title
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Engineering the hydrophobic pocket of carbonic anhydrase ii.
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Authors
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R.S.Alexander,
S.K.Nair,
D.W.Christianson.
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Ref.
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Biochemistry, 1991,
30,
11064-11072.
[DOI no: ]
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PubMed id
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Abstract
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Wild-type and mutant human carbonic anhydrases II, where mutations have been
made in the hydrophobic pocket of the active site, have been studied by X-ray
crystallographic methods. Specifically, mutations at Val-143 (the base of the
pocket) lead to significant changes in catalytic activity and protein structure.
The obliteration of a well-defined pocket in the Val-143----Phe and
Val-143----Tyr mutants results in significantly diminished enzyme activity [(5 x
10(4))-fold and (3 x 10(5))-fold, respectively]; however, the activity of the
Val-143----His mutant is diminished less (10(2)-fold), and deepening the pocket
in the Val-143----Gly mutant results in only a 2-fold decrease in activity
[Fierke et al., 1991 (preceding paper in this issue)]. These results indicate
that the hydrophobic pocket is important for substrate association with the
enzyme, but there are probably several catalytically acceptable substrate
trajectories through this region of the enzyme structure. Additionally, each
mutant protein exhibits long-range (ca. 10-15 A) compensatory structural changes
which accommodate the Val-143 substitution. As such, the genetic-structural
approach represented in this work serves as a three-dimensional paradigm for the
redesign of specificity pockets in other protein catalysts.
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