Action of acetylxylan esterase from Trichoderma reesei on acetylated methyl glycosides |
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Authors: | P Biely G L Ct L Kremnický R V Greene M Tenkanen |
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Institution: | P. Biely, G. L. Côté, L. Kremnický, R. V. Greene,M. Tenkanen |
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Abstract: | Substrate specificity of purified acetylxylan esterase (AcXE) from Trichoderma reesei was investigated on partially and fully acetylated methyl glycopyranosides. Methyl 2,3,4-tri-O-acetyl-β--xylopyranoside was deacetylated at positions 2 and 3, yielding methyl 4-O-acetyl-β--xylopyranoside in almost 90% yield. Methyl 2,3-di-O-acetyl β--xylopyranoside was deacetylated at a rate similar to the fully acetylated derivative. The other two diacetates (2,4- and 3,4-), which have a free hydroxyl group at either position 3 or 2, were deacetylated one order of magnitude more rapidly. Thus the second acetyl group is rapidly released from position 3 or 2 after the first acetyl group is removed from position 2 or 3. The results strongly imply that in degradation of partially acetylated β-1,4-linked xylans, the enzyme deacetylates monoacetylated xylopyranosyl residues more readily than di-O-acetylated residues. The T. reesei AcXE attacked acetylated methyl β--glucopyranosides and β--mannopyranosides in a manner similar to the xylopyranosides. |
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Keywords: | Acetylxylan esterase Substrate specificity Acetylated methyl glycoside Mode of action Trichoderma reesei |
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