In this study, we used a novel α-L-arabinopyranosidase (AbpBs) obtained from ginsenoside-converting Blastococcus saxobsidens that was cloned and expressed in Escherichia coli BL21 (DE3), and then applied it in the biotransformation of ginsenoside Rb₂ into Rd. The gene, termed AbpBs, consisting of 2,406 nucleotides (801 amino acid residues), and with a predicted translated protein molecular mass of 86.4 kDa, was cloned into a pGEX4T-1 vector. A BLAST search using the AbpBs amino acid sequence revealed significant homology with a family 2 glycoside hydrolase (GH2). The over-expressed recombinant AbpBs in Escherichia coli BL21 (DE3) catalyzed the hydrolysis of the arabinopyranose moiety attached to the C-20 position of ginsenoside Rb2 under optimal conditions (pH 7.0 and 40°;C). Kinetic parameters for α-Larabinopyranosidase showed apparent K_m and V_max values of 0.078 ± 0.0002 micrometer and 1.4 ± 0.1 μmol/min/mg of protein against p-nitrophenyl-α-L-arabinopyranoside. Using a purified AbpBs (1 μg/ml), 0.1% of ginsenoside Rb₂ was completely converted to ginsenoside Rd within 1 h. The recombinant AbpBs could be useful for high-yield, rapid, and low-cost preparation of ginsenoside Rd from Rb₂.

中文翻译：

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通过来自 Blastococcus saxobsidens 的重组 α-L-Arabinopyranosidase 将人参皂苷 Rb2 酶促生物转化为 Rd。

在这项研究中，我们使用从人参皂苷转化Blastococcus saxobsidens中获得的一种新型 α-L-阿拉伯吡喃糖苷酶 (AbpBs)，该酶在大肠杆菌BL21 (DE3)中克隆和表达，然后将其应用于人参皂苷 Rb ₂向 Rd 的生物转化。该基因称为AbpBs，由 2,406 个核苷酸（801 个氨基酸残基）组成，预测的翻译蛋白分子量为 86.4 kDa，被克隆到 pGEX4T-1 载体中。使用 AbpBs 氨基酸序列的 BLAST 搜索揭示了与家族 2 糖苷水解酶 (GH2) 的显着同源性。大肠杆菌中过表达的重组 AbpBs在最佳条件（pH 7.0 和 40°；C）下，BL21 (DE3) 催化连接到人参皂苷 Rb2 C-20 位的阿拉伯吡喃糖部分的水解。α-Larabinopyranosidase 的动力学参数显示表观 K _m和 V_最大值为 0.078 ± 0.0002 微米和 1.4 ± 0.1 μmol/min/mg 蛋白质对抗对硝基苯基-α-L-arabinopyranoside。使用纯化的 AbpBs (1 μg/ml)，0.1% 的人参皂苷 Rb ₂在 1 小时内完全转化为人参皂苷 Rd。_{重组AbpBs可用于从Rb 2}高产、快速、低成本地制备人参皂苷Rd 。