Department of Microbiology and Department of Chemistry and Biochemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Appl Environ Microbiol. 1987 Apr;53(4):644-50. doi: 10.1128/aem.53.4.644-650.1987.
Two endoxylanases produced by C. acetobutylicum ATCC 824 were purified to homogeneity by column chromatography. Xylanase A, which has a molecular weight of 65,000, hydrolyzed larchwood xylan randomly, yielding xylohexaose, xylopentaose, xylotetraose, xylotriose, and xylobiose as end products. Xylanase B, which has a molecular weight of 29,000, also hydrolyzed xylan randomly, giving xylotriose and xylobiose as end products. Xylanase A hydrolyzed carboxymethyl cellulose with a higher specific activity than xylan. It also exhibited high activity on acid-swollen cellulose. Xylanase B showed practically no activity against either cellulose or carboxymethyl cellulose but was able to hydrolyze lichenan with a specific activity similar to that for xylan. Both xylanases had no aryl-beta-xylosidase activity. The smallest oligosaccharides degraded by xylanases A and B were xylohexaose and xylotetraose, respectively. The two xylanases demonstrated similar K(m) and V(max) values but had different pH optima and isoelectric points. Ouchterlony immunodiffusion tests showed that xylanases A and B lacked antigenic similarity.
由 C. acetobutylicum ATCC 824 产生的两种内切木聚糖酶通过柱层析法被纯化为均相。分子量为 65000 的木聚糖酶 A 随机水解落叶松木聚糖，生成木六糖、木五糖、木四糖、木三糖和木二糖作为终产物。分子量为 29000 的木聚糖酶 B 也随机水解木聚糖，生成木三糖和木二糖作为终产物。木聚糖酶 A 对羧甲基纤维素的水解比木聚糖具有更高的比活性。它还对酸膨胀纤维素表现出高活性。木聚糖酶 B 对纤维素或羧甲基纤维素几乎没有活性，但能够水解地衣聚糖，其比活性与木聚糖相似。两种木聚糖酶都没有芳基-β-木糖苷酶活性。木聚糖酶 A 和 B 降解的最小寡糖分别为木六糖和木四糖。两种木聚糖酶表现出相似的 K(m)和 V(max)值，但具有不同的 pH 最佳值和等电点。Ouchterlony 免疫扩散试验表明，木聚糖酶 A 和 B 缺乏抗原相似性。
