宇佐美曲霉木聚糖酶的纯化及其性质

宇佐美曲霉E001固态发酵成熟曲经水浸提、硫酸铵盐析、Phenyl-SepharoseCL-4B疏水层析、SephadexG-75凝胶过滤层析、DEAESepharosefastflow阴离子交换层析等提纯步骤,获得了比酶活3047IU/mg蛋白的纯木聚糖酶,其SDS-PAGE呈单一条带。用SDS-PAGE和凝胶过滤测得木聚糖酶的相对分子质量分别为23.2kD和23.0kD,表明该酶蛋白为单亚基。纯木聚糖酶的最适作用温度和pH值分别为50℃和4.6;以燕麦木聚糖为底物的酶动力学常数Km和Vmax值分别为5.27mg/ml和6494μmol/(min·mg);Ca2+、EDTA对酶有激活作用,而Sn2+、Pb2+、Fe3+有强烈的抑制作用。

Purification and Properties of Xylanase from Aspergillus usamii

A xylanase from solid-state fermentation culture of Aspergillus usamii E001 was purified by with water extraction; ammonium sulfate precipitation; and Phenyl-Sepharose CL-4B, Sephadex G-75 and DEAE-Sepharose fast flow column chromatographies. A purified xylanase, showing a single band on SDS-PAGE, was obtained with specific enzyme activity of 3047IU/mg. The molecular weight of the xylanase was determined as 23.2kD on SDS-PAGE and 23.0kD by gel filtration, indicating the xylanase as a monomer. The optimum temperature and pH value for extracting this enzyme were 50℃ and 4.6, respectively. Its kinetics coefficients Km and Vmax with oat spelt xylan as substrate were 5.27mg/ml and 6494mmol/(min·mg), respectively. Its activity was activated by Ca2+ and EDTA, while strongly activated by Sn2+、Pb2+ and Fe3+.