Abstract l -Ribose isomerase ( l RI) is an enzyme that can catalyze the reversible isomerization between l -ribose and l -ribulose. It can also perform the conversion between many aldoses into their corresponding ketoses. l -RI was produced from Cryobacterium sp. N21 (CrL-RIse), and l -ribose was utilized as a substrate. The recombinant l -RI gene was cloned and overexpressed from Cryobacterium sp. N21. The purification of CrL-RIse was performed by metal-affinity chromatography. The enzyme displayed a corresponding band with an approximate size of 35 kDa on the SDS-PAGE analysis. The protein for this gene contains 266 amino acids with an expected molecular weight (Mw) of 29.6 kDa. The measured Mw of CrL-RIse calculated by HPLC was 125 kDa. CrL-RIse was extremely active in glycine buffer at 35 °C, pH 9.0, showing a specific activity of 54.96 U mg−1. CrL-RIse displayed no major increase in activity with metal ions, excluding Mn2+. The estimated Km, Kcat, Kcat/Km and Vmax values of CrL-RIse were 37.8 mM, 10,416 min−1, 275.43 min−1 mM−1, and 250 U mg−1, respectively. The rate of l -ribulose production was 31 % (6.24, 12.11, and 20.89 g L−1) at equilibrium by utilizing 20, 40, and 70 g L−1 of the substrate, respectively. The results indicated that CrL-RIse has the capability to manufacture l -ribulose from l -ribose.

中文翻译：

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从 Cryobacterium sp. 获得的重组 L-核糖异构酶的表征。N21 在 L-核酮糖生产中的潜在应用

摘要 l-核糖异构酶(l RI)是一种能催化l-核糖和l-核酮糖可逆异构化的酶。它还可以将许多醛糖转化为相应的酮糖。l -RI 是从 Cryobacterium sp. 产生的。N21 (CrL-RIse) 和 l-核糖用作底物。从 Cryobacterium sp. 克隆并过表达重组 l-RI 基因。N21。CrL-RIse 的纯化通过金属亲和层析进行。该酶在 SDS-PAGE 分析中显示出相应的条带，其大小约为 35 kDa。该基因的蛋白质包含 266 个氨基酸，预期分子量 (Mw) 为 29.6 kDa。通过 HPLC 计算的 CrL-RIse 的测量 Mw 为 125 kDa。CrL-RIse 在 35 °C、pH 9.0 的甘氨酸缓冲液中非常活跃，比活性为 54.96 U mg-1。CrL-RIse 与金属离子的活性没有显着增加，不包括 Mn2+。CrL-RIse 的估计 Km、Kcat、Kcat/Km 和 Vmax 值分别为 37.8 mM、10,416 min-1、275.43 min-1 mM-1 和 250 U mg-1。在平衡状态下，分别使用 20、40 和 70 g L-1 的底物，L-核酮糖的生产率为 31%（6.24、12.11 和 20.89 g L-1）。结果表明CrL-RIse具有从l-核糖生产l-核酮糖的能力。