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PDBsum entry 1mac
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Hydrolase (glucanase)
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PDB id
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1mac
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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 and site-Directed mutagenesis of bacillus macerans endo-1,3-1,4-Beta-Glucanase.
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Authors
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M.Hahn,
O.Olsen,
O.Politz,
R.Borriss,
U.Heinemann.
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Ref.
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J Biol Chem, 1995,
270,
3081-3088.
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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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In beta-glucans those beta-1,4 glycosidic bonds which are adjacent to beta-1,3
bonds are cleaved by endo-1,3-1,4-beta-glucanases (beta-glucanases). Here, the
relationship between structure and activity of the beta-glucanase of Bacillus
macerans is studied by x-ray crystallography and site-directed mutagenesis of
active site residues. Crystal structure analysis at 2.3-A resolution reveals a
jelly-roll protein structure with a deep active site channel harboring the amino
acid residues Trp101, Glu103, Asp105, and Glu107 as in the hybrid Bacillus
beta-glucanase H(A16-M) (Keitel, T., Simon, O., Borriss, R., and Heinemann, U.
(1993) Proc. Natl. Acad. Sci. U.S.A. 90, 5287-5291). Different mutant proteins
with substitutions in these residues are generated by site-directed mutagenesis,
isolated, and characterized. Compared with the wild-type enzyme their activity
is reduced to less than 1%. Several mutants with isosteric substitutions in
Glu103 and Glu107 are completely inactive, suggesting a direct role of these
residues in glycosyl bond hydrolysis. The kinetic properties of mutant
beta-glucanases and the crystal structure of the wild-type enzyme are consistent
with a mechanism where Glu103 and Glu107 are the catalytic amino acid residues
responsible for cleavage of the beta-1,4 glycosidic bond within the substrate
molecule.
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Secondary reference #1
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Title
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Molecular and active-Site structure of a bacillus 1,3-1,4-Beta-Glucanase.
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Authors
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T.Keitel,
O.Simon,
R.Borriss,
U.Heinemann.
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Ref.
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Proc Natl Acad Sci U S A, 1993,
90,
5287-5291.
[DOI no: ]
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PubMed id
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