Subray SH, Ameeta RK, Krishna NG, Khan IM. Catalytic thiol and carboxylate: role of cysteine and glutamic acid in the xylosidic activity of endoxylanase from Chainia sp. (NCL 82-5-1).
Arch Biochem Biophys 1998;
355:153-9. [PMID:
9675021 DOI:
10.1006/abbi.1998.0729]
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Abstract
Chemical modification of the endoxylanase from Chainia sp. with group-specific chemical modifiers in the absence and presence of substrate and kinetics of modification revealed the involvement of a thiol and a carboxylate in the catalytic function of the enzyme. The active-site peptides were chemically labeled and sequenced. The sequence alignment of the chemically labeled peptide with other family G/11 xylanases showed that the catalytic glutamate of Chainia xylanase is located in a highly homologous region and may function as an acid/base catalyst while thiol of the Cys may function as a nucleophile.
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