嗜热毛壳菌内切β-葡聚糖酶的分离纯化及特性

探讨了液体发酵嗜热毛壳菌（Chaetomium thermophile)产生的内切β－葡聚糖酶的分离纯化及特性。粗酶液经硫酸铵分级沉淀，DEAE－Seplharose Fast Flow阴离子层析，Pheny1-Sepha-rose疏水层析，Sephacry1 S-100分子筛层析等步骤便可获得凝胶电泳均一的内切β－葡聚糖酶，经12．5％SDS－PAGE和凝胶过滤层析法分离纯化酶蛋白的分子量约为67．8kD的69．8kD。该酶反应的最适温度和pH分别为60℃和4．0－4．5在pH5.0条件下，该酶在60℃下稳定：70℃保温1h后，仍保留30％的活性；在80摄氏度的半衰期为25min，金属离子内切β－葡聚糖酶的活性影响较大，其中Na^ 对酶有激活作用；Fe^2 ,Ag^ ,Cu^2 ,Ba^2 ,Zn^2 等对酶有抑制作用。该酶对结晶纤维素有没水解能力。

Purification and Properties of An Endocellulase from The Thermophilic Fungus Chaetomium thermophile

An endocellulase from culture supernatant of a thermophilic fungus Chaetomium thermophile was purifided to homogeneity, by using ammonium sulfate fraction, DEAE-Sepharose Fast-flow chromatography, Phenyl-Sepharose Fast Flow chromatography and Sephacryl S-100 chromatography. The enzyme was a glycoprotein with an apparent molecular weight of 67,800 and 69,800, as determinded by 12.5% SDS-PAGE and gel filtration respectively. The endocellulase was optimally active at pH 4.0-4.5 and 60 degrees C. It was thermostable at 60 degrees C and retained 30% activity after 60 min at 70 degrees C. The half life time of the enzyme at 80 degrees C was 25 min. Different metal ions showed different effects on the endocellulase activity. Na+ enhanced the enzyme activity, whereas Fe2+, Ag+, Cu2+, Ba2+ and Zn2+ cause obvious inhibition. But it didn't work on crystalline cellulose.