Shao W, Wiegel J
Department of Microbiology, University of Georgia, Athens 30602, USA.
Appl Environ Microbiol. 1995 Feb;61(2):729-33. doi: 10.1128/aem.61.2.729-733.1995.
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 degrees C and at pH 7.5 and 84 degrees C, respectively. Km 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 degrees and slightly above 100 degrees C, respectively.
从嗜热栖热放线菌JW/SL-YS485中纯化出两种乙酰酯酶（EC 3.1.1.6），该菌为厌氧嗜热芽孢杆菌，能够利用多种取代木聚糖进行生长。两种酶均可从化学乙酰化的落叶松木聚糖中释放出乙酸。乙酰木聚糖酯酶I和II的分子量分别为195 kDa和106 kDa，亚基分子量分别为32 kDa（酯酶I）和26 kDa（酯酶II）。其等电点分别为4.2和4.3。以乙酸4-甲基伞形酮酯为底物进行2分钟测定，乙酰木聚糖酯酶I和II的最佳活性分别出现在pH 7.0和80℃以及pH 7.5和84℃。乙酰木聚糖酯酶I和II对乙酸4-甲基伞形酮酯的Km值分别为0.45 mM和0.52 mM。在pH 7.0时，乙酰木聚糖酯酶I和II的1小时半衰期温度分别为75℃和略高于100℃。
