1BCX

MUTATIONAL AND CRYSTALLOGRAPHIC ANALYSES OF THE ACTIVE SITE RESIDUES OF THE BACILLUS CIRCULANS XYLANASE

Summary for 1BCX

• Entry DOI: 10.2210/pdb1bcx/pdb
• Related PRD ID: PRD_900116
• Descriptor: XYLANASE, beta-D-xylopyranose-(1-4)-beta-D-xylopyranose, SULFATE ION, ... (4 entities in total)
• Functional Keywords: hydrolase(xylan degradation)
• Biological source: Bacillus circulans
• Total number of polymer chains: 1
• Total formula weight: 20761.34

Authors

Campbell, R.L.,Wakarchuk, W.W. (deposition date: 1994-04-01, release date: 1994-10-15, Last modification date: 2024-02-07)

Primary citation

Wakarchuk, W.W.,Campbell, R.L.,Sung, W.L.,Davoodi, J.,Yaguchi, M.
Mutational and crystallographic analyses of the active site residues of the Bacillus circulans xylanase.
Protein Sci., 3:467-475, 1994

PubMed Abstract: 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.

PubMed: 8019418

Experimental method

X-RAY DIFFRACTION (1.81 Å)