【摘要】 研究了嗜热毛壳菌Chaetomiumthermophilum液体发酵产生的一种胞外β-葡萄糖苷酶的分离纯化及特性。粗酶液经硫酸铵沉淀、DEAE-SepharoseFastFlow阴离子层析、Phenyl-Sepharose疏水层析、SephacrylS-100分子筛层析等步骤后获得凝胶电泳均一的β-葡萄糖苷酶。经10%SDS-PAGE和凝胶过滤层析方法分别测得该酶的分子量大小约为118.0kDa和120.1kDa。该酶反应的最适温度为70℃,最适pH值为4.0~5.0。有高的热稳定性,在60℃保温1小时酶活性不丧失,在70℃时的半衰期为16min,在90℃保温10min仍具有7.6%的活性。且能在pH4.0~11.0之间保持稳定。金属离子对β-葡萄糖苷酶的活性影响较大,其中Ca2+、Ba2+对酶有激活作用,而Zn2+、Cu2+、Al3+、Ag+、Hg2+对酶有显著的抑制作用。更多还原

【Abstract】 β-Glucosidase is an important component of the cellulase complex. It not only hydrolyzes cellobiose and short-chain cellooligosaccharides to glucose, but also removes the inhibitory effect of cellobiose on the β-1, 4-endoglucanase and exoglucanase, thereby increasing the overall rate of cellulose biodegradation. β-Glucosidase from culture supernatant of a thermophilic fungus Chaetomium thermophilum was purified to homogeneity, by using ammonium sulfate fraction, DEAE-sepharose fast flow chromatography, phenyl-sepharose fast flow chromatography and sephacryl S-100 chromatography, and its properties were studied. The molecular mass of the enzyme is about between 118.0kDa to 120.1kDa, as identified by 10% SDS-PAGE and gel filtration correspondingly. Its optimum pH value and temperature are 4.0~5.0 and 70℃ respectively. It is stable in pH 4.0~11.0 and under 60℃. Different metal ions show different effects on the β-glucosidase activity. Ca2+ and Ba2+ will enhance its activity, while Zn2+, Cu2+, Al3+, Ag+ and Hg2+ will cause obvious inhibition.更多还原