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PDBsum entry 1ded
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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 alkalophilic asparagine 233-Replaced cyclodextrin glucanotransferase complexed with an inhibitor, Acarbose, At 2.0 a resolution.
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Authors
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N.Ishii,
K.Haga,
K.Yamane,
K.Harata.
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Ref.
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J Biochem (tokyo), 2000,
127,
383-391.
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PubMed id
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Abstract
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The product specificity of cyclodextrin glucanotransferase (CGTase) from
alkalophilic Bacillus sp. #1011 is improved to near-uniformity by mutation of
histidine-233 to asparagine. Asparagine 233-replaced CGTase (H233N-CGTase) no
longer produces alpha-cyclodextrin, while the wild-type CGTase from the same
bacterium produces a mixture of predominantly alpha-, beta-, and
gamma-cyclodextrins, catalyzing the conversion of starch into cyclic or linear
alpha-1,4-linked glucopyranosyl chains. In order to better understand the
protein engineering of H233N-CGTase, the crystal structure of the mutant enzyme
complexed with a maltotetraose analog, acarbose, was determined at 2.0 A
resolution with a final crystallographic R value of 0.163 for all data. Taking a
close look at the active site cleft in which the acarbose molecule is bound, the
most probable reason for the improved specificity of H233N-CGTase is the removal
of interactions needed to form a compact ring like a-cyclodextrin.
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