Purification and characterization of two thermostable acetyl xylan esterases from Thermoanaerobacterium sp. strain JW/SL-YS485
- Univ. of Georgia, Athens, GA (United States)
Two acetyl esterases (EC 3.1.1.6) were purified to gel electrophoretic homogeneity from Thermoanaerobacterium sp. strain JW/SL-YS485, an anaerobic, thermophilic endospore former which is able to utilize various substituted xylans for growth. Both enzymes released acetic acid from chemically acetylated larch xylan. Acetyl xylan esterases I and II had molecular masses of 195 and 106 kDa, respectively, with subunits of 32 kDa (esterase I) and 26 kDa (esterase II). The isoelectric points were 4.2 and 4.3, respectively. As determined by a 2-min assay with 4-methylumbelliferyl acetate as the substrate, the optimal activity of acetyl xylan esterases I and II occurred at pH 7.0 and 80{degree}C and at pH 7.5 and 84{degree}C, respectively. K{sub m} values of 0.45 and 0.52 mM 4-methylumbelliferyl acetate were observed for acetyl xylan esterases I and II, respectively. At pH 7.0, the temperatures for the 1-h half-lives for acetyl xylan esterases I and II were 75{degree} and slightly above 100{degree}C, respectively.
- OSTI ID:
- 621396
- Journal Information:
- Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 2 Vol. 61; ISSN AEMIDF; ISSN 0099-2240
- Country of Publication:
- United States
- Language:
- English
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