School of Life Science, University of Science and Technology of China, Hefei, 230027 Anhui, People's Republic of China.
Mol Biotechnol. 2013 Feb;53(2):159-69. doi: 10.1007/s12033-012-9508-9.
Xylitol dehydrogenase (XDH) (EC 1.1.1.9) is one of the key enzymes in the xylose fermentation pathway in yeast and fungi. A xylitol dehydrogenase gene (XYL2) encoding a XDH was cloned from Kluyveromyces marxianus NBRC 1777, and the in vivo function was validated by disruption and complementation analysis. The highest activity of KmXDH could be observed at pH 9.5 during 55°C. The values of k(cat)/K(m) indicate that KmXDH prefers NAD(+) to NADP(+) (k(cat)/K(m NAD)(+) 3681/min mM and k(cat)/K(m NADP)(+) 1361/min mM). The different coenzyme preference between KmXR and KmXDH caused an accumulation of NADH in the xylose utilization pathway. The redox imbalance may be one of the reasons to cause the poor xylose fermentation under oxygen-limited conditions in K. marxianus NBRC1777.
木酮糖脱氢酶（XDH）（EC 1.1.1.9）是酵母和真菌木糖发酵途径中的关键酶之一。从马克斯克鲁维酵母 NBRC 1777 中克隆了编码 XDH 的木酮糖脱氢酶基因（XYL2），并通过敲除和互补分析验证了其体内功能。KmXDH 的最高活性可在 55°C 时 pH9.5 下观察到。k(cat)/K(m)值表明 KmXDH 优先选择 NAD(+)而不是 NADP+(k(cat)/K(m NAD)(+) 3681/min mM 和 k(cat)/K(m NADP)(+) 1361/min mM)。KmXR 和 KmXDH 对辅酶的不同偏好导致木糖利用途径中 NADH 的积累。氧化还原失衡可能是马克斯克鲁维酵母 NBRC1777 在限氧条件下木糖发酵不良的原因之一。
