球孢白僵菌胞内几丁质酶的分离纯化及性质

PURIFICATION AND PROPERTIES OF INTRACELLULAR CHITINASE FROM BEAUVERIA BASSIANA

球孢白僵菌(Beauveria bassiana)突变株CH-1316细胞裂解液经(NH_4)_2SO_4沉淀,DEAE-纤维素层析及凝胶过滤,分离出一种几丁质酶,该酶的分子量为32000;最适pH为5.0;最适温度为40℃;最适离子强度为0.2mol/L NaCl;Hg^(2+)、Fe^(2+)是该酶的强抑制剂;该几丁质酶完全不水解纯的片状几丁质,脱矿几丁质也不是该酶的良好底物;该几丁质酶水解几丁寡糖,但不水解几丁二糖;对几丁五糖以上的寡糖水解速度较快,而对几丁三糖和四糖水解速度则慢得多。

An intracellular chitinase from Beauveria bassiana mutant CH-1316 was purified to homogeneous by (NH4)2SO4 precipitation, DEAE-cellulose chromatog-raphy and Sephadex G-100 chromatography. The enzyme had a molecular weight of 32000. The optimum pH, temperature and ionic strength for activity were 5.0, 40℃ and 0.2mol/L Nad respectively. Hg2+ and Fe2+ strongly inhibited the activity. The enzyme showed no activity on purified flaked chitin, little activity on de-mineralized chitin. The enzyme hydrolyses oligosaccharides with different rate. Chitohexaose and chitopenaose were hydrolyzed much faster than chitotetraose and chitotriose. Chitobiose can hardly be hydrolysed.