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Proc Natl Acad Sci U S A. 1993 Jun 1;90(11):5287-91.

Molecular and active-site structure of a Bacillus 1,3-1,4-beta-glucanase.

Author information

1
Institut für Kristallographie, Freie Universität, Berlin, Federal Republic of Germany.

Abstract

The three-dimensional structure of the hybrid Bacillus 1,3-1,4-beta-glucanase (beta-glucanase; 1,3-1,4-beta-D-glucan 4-glucanohydrolase, lichenase, EC 3.2.1.73) designated H(A16-M) was determined by x-ray crystallography at a resolution of 2.0 A and refined to an R value of 16.4% using stereochemical restraints. The protein molecule consists mainly of two seven-stranded antiparallel beta-pleated sheets arranged atop each other to form a compact, sandwich-like structure. A channel crossing one side of the protein molecule accommodates an inhibitor, 3,4-epoxybutyl beta-D-cellobioside, which binds covalently to the side chain of Glu-105, as seen in a crystal structure analysis at 2.8-A resolution of the protein-inhibitor complex (R = 16.8%). That Glu-105 may be indispensible for enzyme catalysis by H(A16-M) is suggested by site-directed mutagenesis of this residue, which inevitably leads to an inactive enzyme.

PMID:
8099449
PMCID:
PMC46701
DOI:
10.1073/pnas.90.11.5287
[Indexed for MEDLINE]
Free PMC Article

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