1bcx | pdb_00001bcx
MUTATIONAL AND CRYSTALLOGRAPHIC ANALYSES OF THE ACTIVE SITE RESIDUES OF THE BACILLUS CIRCULANS XYLANASE
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Overview
Using site-directed mutagenesis we have investigated the catalytic, residues in a xylanase from Bacillus circulans. Analysis of the mutants, E78D and E172D indicated that mutations in these conserved residues do not, grossly alter the structure of the enzyme and that these residues, participate in the catalytic mechanism. We have now determined the crystal, structure of an enzyme-substrate complex to 108 A resolution using a, catalytically incompetent mutant (E172C). In addition to the catalytic, residues, Glu 78 and Glu 172, we have identified 2 tyrosine residues, Tyr, 69 and Tyr 80, which likely function in substrate binding, and an arginine, residue, Arg 112, which plays an important role in the active site of this, enzyme. On the basis of our work we would propose that Glu 78 is the, nucleophile and that Glu 172 is the acid-base catalyst in the reaction.
About this Structure
1BCX is a Single protein structure of sequence from Bacillus circulans with SO4 as ligand. Active as Endo-1,4-beta-xylanase, with EC number 3.2.1.8 Full crystallographic information is available from OCA.
Reference
Mutational and crystallographic analyses of the active site residues of the Bacillus circulans xylanase., Wakarchuk WW, Campbell RL, Sung WL, Davoodi J, Yaguchi M, Protein Sci. 1994 Mar;3(3):467-75. PMID:8019418
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