采用不同化学修饰剂对毕赤酵母工程菌所产的木聚糖酶进行化学修饰,结果发现用聚乙二醇(diamino-PEG)对酶进行的化学修饰,提高了酶的热稳定性。通过对化学修饰木聚糖酶条件的优化,最终确定了修饰反应体系中,木聚糖酶、diamino-PEG和偶联剂(EDAC/NHS试剂)的摩尔比为1∶1 000∶100。该修饰反应得到的修饰酶,在55℃保温10 min后,残余酶活力为61.6%,比原酶提高了29.1%,通过对酶学性质的分析,发现修饰酶只有pH稳定性、热稳定性发生了改变。

The xylanase produced from Picha pastoris was modified with different chemical reagents.The results indicated that the thermostability of the xylanase modified with diamino-PEG was improved.The modification condition of the xylanase with diamino-PEG was optimized.The molar ration of xylanase/ diamino-PEG/ EDAC/NHS was 1/1000/100.The relative residual activity of modified xylanase by using this condition was 61.6% after incubated 10 min at 55℃,over 29.1% than unmodified xylanase.The analysis of the characteristics of enzymological assay of the modified xylanase found that only the pH stability and thermostability changed.