热带假丝酵母木糖还原酶的酶学性质研究  

The Characterizations of Xylose Reductase in Candida tropicalis

作　　者：曾琦锴[1] 林影[1] 陈璐菲[1] 庞冲[1] 

机构地区：[1]华南理工大学生物科学与工程学院,广州510641

出　　处：《食品与发酵工业》2006年第7期16-18,共3页Food and Fermentation Industries

基　　金：广东省自然科学基金(04020051)资助项目

摘　　要：研究了从热带假丝酵母(Candida tropicalis)菌体中获得的木糖还原酶(XR)的酶学性质。实验结果证实,C.tropicalis的细胞浆粗提液经盐析、透析及阴离子交换柱层析后得到的酶液中木糖还原酶比酶活为9·3U/mg、最适酶反应pH为6·0、最适反应温度为35℃;以木糖为底物时,Km·Xyl为64·8mmol/L、Km·N·X为0·0622mmol/L;以阿拉伯糖为底物时,Km·Ara为172mmol/L、Km·N·A为0·0375mmol/L。Zn2+是木糖还原酶的激活剂,Fe3+为抑制剂。固定木糖为反应底物,分别以NADPH及NADH为辅酶测定酶活,实验结果显示该菌体中木糖还原酶的活性主要依赖于辅酶NADPH。A xylose reductase（XR）from Candida tropicalis, a key enzyme in the production of xylitol and conversion of xylose to ethanol, was characterized in the purified solution by an anion- exchange column. The XR in purified solution by an anion- exchange, with the specific activity 9.3 U/mg, was optimally active at 35℃, pH 6.0 with the Km values of 64.8 mmol/L and 172 mmol/L for xylose and arabinose respectively. In these conditions the Km values for NADPH were 0. 062 2 mmol/L and 0. 037 5 mmol/L with xylose and arabinose as the substrates respectivel. Zn2 ＋ can increased XR activity and Fe^3 ＋ can inhibited XR activity in the isolated solution. At the same time, we compared the substrate affinity between NADH and NADPH and found that the XR activity in Candida tropicalis is mostly depended on NADPH.

关 键 词：木糖还原酶(XR) 酶学性质 热带假丝酵母(Candida tropicalis) 

分 类 号：Q936[生物学—微生物学]