Abstract

A novel arabitol dehydrogenase (ArDH) gene was cloned from a bacterium named Aspergillus nidulans and expressed heterologously in Escherichia coli. The purified ArDH exhibited the maximal activity in pH 9.5 Tris-HCl buffer at 40 °C, showed K_m and V_max of 1.2 mg/mL and 9.1 U/mg, respectively. The ArDH was used to produce the L-xylulose and coupled with the NADH oxidase (Nox) for the regeneration of NAD⁺. In further optimization, a high conversion of 84.6% in 8 hours was achieved under the optimal conditions: 20 mM of xylitol, 100 µM NAD⁺ in pH 9.0 Tris-HCl buffer at 30 °C. The results indicated the coupling system with cofactor regeneration provides a promising approach for L-xylulose production from xylitol.

摘要

一种新的阿糖醇脱氢酶 (ArDH) 基因从一种名为构巢曲霉的细菌中克隆出来，并在大肠杆菌中异源表达。纯化的 ArDH 在 40 °C 时在 pH 9.5 Tris-HCl 缓冲液中表现出最大活性，K _m和V _max分别为 1.2 mg/mL 和 9.1 U/mg。ArDH 用于生产 L-木酮糖并与 NADH 氧化酶 (Nox) 偶联以再生 NAD ⁺。在进一步优化中，在最佳条件下实现了 8 小时内 84.6% 的高转化率：20 mM 木糖醇，100 µM NAD ⁺在 30 °C 的 pH 9.0 Tris-HCl 缓冲液中。结果表明，具有辅因子再生的偶联系统为木糖醇生产L-木酮糖提供了一种有前景的方法。