Structure of the Bacillus agaradherans family 5 endoglucanase at 1.6 A and its cellobiose complex at 2.0 A resolutionDavies, G.J., Dauter, M., Brzozowski, A.M., Bjornvad, M.E., Andersen, K.V., Schulein, M.
(1998) Biochemistry 37: 1926-1932
- PubMed: 9485319
- DOI: 10.1021/bi972162m
- Primary Citation of Related Structures:
- PubMed Abstract:
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 ...
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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