d-Ribulose and l-fuculose are potentially valuable rare sugars useful for anticancer and antiviral drugs in the agriculture and medicine industries. These rare sugars are usually produced by chemical methods, which are generally expensive, complicated and do not meet the increasing demands. Furthermore, the isomerization of d-arabinose and l-fucose byDd-arabinose and l-fucose by d-arabinose isomerase from bacterial sources for the production of d-ribulose and l-fuculose have not yet become industrial due to the shortage of biocatalysts, resulting in poor yield and high cost of production. In this study, a thermostable d-ribulose- and l-fuculose producing d-arabinose isomerase from the bacterium Thermanaeromonas toyohensis was characterized. The recombinant d-arabinose isomerase from T. toyohensis (Thto-DaIase) was purified with a single band at 66 kDa using His-trap affinity chromatography. The native enzyme existed as a homotetramer with a molecular weight of 310 kDa, and the specific activities for both d-arabinose and l-fucose were observed to be 98.08 and 85.52 U mg-1, respectively. The thermostable recombinant Thto-DaIase was activated when 1 mM Mn2+ was added to the reactions at an optimum pH of 9.0 at 75 °C and showed approximately 50% activity for both d-arabinose and l-fucose at 75 °C after 10 h. The Michaelis-Menten constant (Km), the turnover number (kcat) and catalytic efficiency (kcat/Km) for d-arabinose/l-fucose were 111/81.24 mM, 18,466/10,688 min-1, and 166/132 mM-1 min-1, respectively. When the reaction reached to equilibrium, the conversion rates of d-ribulose from d-arabinose and l-fuculose from l-fucose were almost 27% (21 g L-1) and 24.88% (19.92 g L-1) from 80 g L-1 of d-arabinose and l-fucose, respectively.

中文翻译：

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来自丰隆产热单胞菌的新型 D-阿拉伯糖异构酶的表征及其在 D-核酮糖和 L-岩藻糖生产中的应用

d-核酮糖和 l-岩藻糖是具有潜在价值的稀有糖，可用于农业和医药行业的抗癌和抗病毒药物。这些稀有糖通常通过化学方法生产，通常价格昂贵、复杂且不能满足日益增长的需求。此外，由于生物催化剂的短缺，用于生产 d-核酮糖和 l-岩藻糖的细菌来源的 D-阿拉伯糖和 l-岩藻糖通过 D-阿拉伯糖异构化和 l-岩藻糖的 d-阿拉伯糖和 l-岩藻糖异构化尚未实现工业化，导致产量低，生产成本高。在这项研究中，对来自丰水产热单胞菌的热稳定 d-核酮糖和 l-岩藻糖生产 d-阿拉伯糖异构酶进行了表征。来自 T 的重组 d-阿拉伯糖异构酶。toyohensis (Thto-DaIase) 使用His-trap 亲和层析纯化为 66 kDa 的单条带。天然酶以分子量为 310 kDa 的同源四聚体形式存在，观察到 d-阿拉伯糖和 l-岩藻糖的比活性分别为 98.08 和 85.52 U mg-1。热稳定的重组 Thto-DaIase 在 75°C、9.0 的最佳 pH 值下加入 1 mM Mn2+ 时被激活，10 小时后在 75°C 下对 d-阿拉伯糖和 l-岩藻糖显示约 50% 的活性。d-阿拉伯糖/l-岩藻糖的 Michaelis-Menten 常数 (Km)、转换数 (kcat) 和催化效率 (kcat/Km) 为 111/81.24 mM、18,466/10,688 min-1 和 166/132 mM-分别为 1 min-1。当反应达到平衡时，