Cloning and characterization of a novel recombinant multifunctional glycoside hydrolase β-D-xylosidase/α-L-arabinopyranosidase/β-glucosidase from <i>Bifidobacterium adolescentis</i> and its application on the biotransformation of ginsenoside Rb3

β-D-xylosidase, an important glycoside hydrolase, hydrolyzes xylo-oligosaccharides to yield xylose and biotransforms specific saponins by cleaving β-xylose at the non-reducing end. It is extensively employed in renewable resources, including fuels, food, and pharmaceuticals, as a xylanolytic enzyme. In this study, a 1197 bp β-xylosidase gene (BaXyl5B) derived from <i>Bifidobacterium adolescentis</i> was cloned and expressed in <i>E. coli</i> BL21. Following purification, the recombinant β-xylosidase exhibited a distinct band on SDS-PAGE; its molecular weight was determined to be 46.4 kDa. The optimal activity of BaXyl5B was observed at a pH of 6.0 and a temperature of 30 °C. Purified BaXyl5B demonstrated multifunctional activities involving <i>p</i>-nitrophenyl-β-D-xylopyranoside (<i>p</i>NPβXyl), <i>p</i>-nitrophenyl-α-L-arabinopyranoside (<i>p</i>NPαArap), and <i>p</i>-nitrophenyl-β-D-glucopyranoside (<i>p</i>NPβGlc). A significant finding of this study was that BaXyl5B exhibited high selectivity towards ginsenoside Rb3, which could hydrolyze xylose at the C-20 position of Rb3 to yield Rd and F2. Overall, this research explored a novel β-xylosidase, BaXyl5B, that could serve as a valuable biocatalyst for converting ginsenosides and synthesizing active glycosides and aglycones, making it a promising enzyme for further exploration and utilization.

β-D-木糖苷酶（β-D-xylosidase）是一类重要的糖苷水解酶（glycoside hydrolase），可通过切割非还原端的β-木糖基水解木寡糖生成木糖，并对特定皂苷进行生物转化。作为一种木聚糖降解酶，该酶被广泛应用于燃料、食品与制药等可再生资源相关领域。本研究从青春双歧杆菌（Bifidobacterium adolescentis）中克隆得到一段长度为1197 bp的β-D-木糖苷酶基因BaXyl5B，并将其在大肠杆菌BL21（E. coli BL21）中进行异源表达。纯化后的重组β-D-木糖苷酶在SDS-PAGE上呈现单一清晰条带，经测定其分子质量为46.4 kDa。BaXyl5B的最适反应pH为6.0，最适反应温度为30℃。纯化的BaXyl5B展现出多重底物催化活性，可作用于对硝基苯基-β-D-吡喃木糖苷（p-nitrophenyl-β-D-xylopyranoside, pNPβXyl）、对硝基苯基-α-L-吡喃阿拉伯糖苷（p-nitrophenyl-α-L-arabinopyranoside, pNPαArap）以及对硝基苯基-β-D-吡喃葡萄糖苷（p-nitrophenyl-β-D-glucopyranoside, pNPβGlc）。本研究的一项重要发现是，BaXyl5B对人参皂苷Rb3具有高度底物选择性，可水解其C-20位连接的木糖基，生成人参皂苷Rd与F2。综上，本研究发掘了一种新型β-D-木糖苷酶BaXyl5B，其可作为极具应用价值的生物催化剂，用于人参皂苷的转化以及活性糖苷与苷元的合成，是一款具备进一步开发与应用潜力的酶制剂。

搜集汇总

背景与挑战

背景概述

该数据集总结了一项关于从青春双歧杆菌中克隆和表征新型重组多功能糖苷水解酶BaXyl5B的研究。该酶具有β-D-木糖苷酶、α-L-阿拉伯吡喃糖苷酶和β-葡萄糖苷酶活性，并在pH 6.0和30°C下表现出最佳活性。关键应用是高效选择性水解人参皂苷Rb3，生成人参皂苷Rd和F2，使其成为生物转化和活性糖苷合成的有前景的生物催化剂。