Optimal activity and thermostability of xylose reductase from Debaryomyces hansenii UFV-170
Optimal activity and thermostability of xylose reductase from Debaryomyces hansenii UFV-170
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DOI：
10.1007/s10295-008-0498-3
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发表时间：
2009-02
影响因子：
3.4
通讯作者：
F. C. Sampaio;J. T. Faria;Flávia M. Lopes Passos;A. Converti;L. A. Minin
中科院分区：
文献类型：
--
作者：
F. C. Sampaio;J. T. Faria;Flávia M. Lopes Passos;A. Converti;L. A. Minin
木糖还原酶（XR）是催化木糖代谢第一步的酶。虽然来自各种酵母的XRs已被表征，但对汉逊德巴利酵母中的这种酶知之甚少。在本研究中，响应面分析，以确定最佳条件福特。hanseniUFV-170 XR活性。pH和温度的影响，范围分别从4.0至8.0和从25至55°C，通过22中心复合设计面心评价。采用方差分析（ANOVA）和t检验分别对模型和回归系数进行统计学显著性检验。NADPH依赖的XR活性范围为0.502 - 2.53 U mL−1，相当于0.07-0.352 U mg−1，而NADH依赖的XR活性几乎可以忽略不计。该模型预测在pH 5.3和39°C下具有令人满意的相关性（R2= 0.940），最大体积活性为2.27 U mL− 1，比活性为0.300 U mg− 1，这通过在这些条件下进行的额外测试得到了相当好的证实。证明该酶在低温（4°C）下非常稳定，在360分钟后几乎完全保持其活性，这对应于39°C下的半衰期。另一方面，在≥50°C的温度下，仅在20分钟后就几乎完全丧失。
Xylose reductase (XR) is the enzyme that catalyzes the first step of xylose metabolism. Although XRs from various yeasts have been characterized, little is known about this enzyme inDebaryomyces hansenii. In the present study, response surface analysis was used to determine the optimal conditions forD. hanseniiUFV-170 XR activity. The influence of pH and temperature, ranging from 4.0 to 8.0 and from 25 to 55°C, respectively, was evaluated by a 22central composite design face-centered. TheF-test (ANOVA) and the Student’sttest were performed to evaluate the statistical significance of the model and the regression coefficients, respectively. The NADPH-dependent XR activity varied from 0.502 to 2.53 U mL−1, corresponding to 0.07–0.352 U mg−1, whereas the NADH-dependent one was almost negligible. The model predicted with satisfactory correlation (R2= 0.940) maximum volumetric activity of 2.27 U mL−1and specific activity of 0.300 U mg−1at pH 5.3 and 39°C, which were fairly confirmed by additional tests performed under these conditions. The enzyme proved very stable at low temperature (4°C), keeping its activity almost entirely after 360 min, which corresponded to the half-time at 39°C. On the other hand, at temperatures ≥50°C it was lost almost completely after only 20 min.