绵毛嗜热丝孢菌木聚糖酶的纯化与性质

Purification and characterization of an extracellular xylanase from Thermomyces lanuginosus

研究了绵毛嗜热丝孢菌Thermomyces lanuginosus W205胞外木聚糖酶的纯化与性质。粗酶液经硫酸铵沉淀和Q-Sepharose FF离子交换层析即可得到电泳纯木聚糖酶,回收率为46.6%,比酶活为1396.9U/mg。该酶的最适pH和最适温度分别为pH7.0和75℃,pH稳定范围为5.5-10.8,70℃处理30min残存酶活在70%以上。薄层层析结果显示该酶水解桦木木聚糖的主要产物是木二糖和木三糖,并且能够通过转糖苷作用将木三糖转化为木二糖。该木聚糖酶易于纯化并且具有较宽的pH稳定性及良好的热稳定性,具有较大的潜在工业应用价值。

Purification and characterization of an extracellular xylanase produced by Thermomyces lanuginosus W205 was studied. The enzyme was purified to homogeneity by ammonium sulfate precipitation followed by anion exchange chromatography on Q-Sepharose FF colunm, with 46.6% yield and 1396.9U/mg specific activity. The optimal temperature and pH for the xylanase activity was 75℃ and pH 7.0, respectively. The xylanase was stable within pH 5.5-- 10. The residual activity was up to 70% after the enzyme was incubated at 70℃ for 30min. Thin-layer chromatography （TLC） analysis showed that the xylanase released mainly xylobiose and xylotriose from birchwood xylan. The hydrolysis of xylotriose appeared to proceed via transglycosylation, since the xylobiose was the predominant product. Easy purification from the fermentation broth and its good pH and thermal stability will be highly useful for its industrial application.