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PDBsum entry 1a3h
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References listed in PDB file
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Key reference
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Title
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Structure of the bacillus agaradherans family 5 endoglucanase at 1.6 a and its cellobiose complex at 2.0 a resolution.
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Authors
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G.J.Davies,
M.Dauter,
A.M.Brzozowski,
M.E.Bjørnvad,
K.V.Andersen,
M.Schülein.
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Ref.
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Biochemistry, 1998,
37,
1926-1932.
[DOI no: ]
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PubMed id
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Abstract
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The enzymatic degradation of cellulose, by cellulases, is not only industrially
important in the food, paper, and textile industries but also a potentially
useful method for the environmentally friendly recycling of municipal waste. An
understanding of the structural and mechanistic requirements for the hydrolysis
of the beta-1,4 glycosidic bonds of cellulose is an essential prerequisite for
beneficial engineering of cellulases for these processes. Cellulases have been
classified into 13 of the 62 glycoside hydrolase families [Henrissat, B., and
Bairoch, A. (1996) Biochem J. 316, 695-696]. The structure of the catalytic core
of the family 5 endoglucanase, Ce15A, from the alkalophilic Bacillus
agaradherans has been solved by multiple isomorphous replacement at 1.6 A
resolution. Ce15A has the (alpha/beta)8 barrel structure and signature
structural features typical of the grouping of glycoside hydrolase families
known as clan GH-A, with the catalytic acid/base Glu 139 and nucleophile Glu 228
on barrel strands beta 4 and beta 7 as expected. In addition to the native
enzyme, the 2.0 A resolution structure of the cellobiose-bound form of the
enzyme has also been determined. Cellobiose binds preferentially in the -2 and
-3 subsites of the enzyme. Kinetic studies on the isolated catalytic core domain
of Ce15A, using a series of reduced cellodextrins as substrates, suggest
approximately five to six binding sites, consistent with the shape and size of
the cleft observed by crystallography.
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