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A Versatile β-Glycosidase from Petroclostridium xylanilyticum Prefers the Conversion of Ginsenoside Rb3 over Rb1, Rb2, and Rc to Rd by Its Specific Cleavage Activity toward 1,6-Glycosidic Linkages
Journal of Agricultural and Food Chemistry ( IF 5.7 ) Pub Date : 2024-07-25 , DOI: 10.1021/acs.jafc.4c03909
Wenqi Xu 1 , Cuicui Duan 1 , Fumin Ma 1 , Dan Li 1, 2 , Xiaolei Li 1, 2
Affiliation  

To convert ginsenosides Rb1, Rb2, Rb3, and Rc into Rd by a single enzyme, a putative β-glycosidase (Pxbgl) from the xylan-degrading bacterium Petroclostridium xylanilyticum was identified and used. The kcat/Km value of Pxbgl for Rb3 was 18.18 ± 0.07 mM–1/s, which was significantly higher than those of Pxbgl for other ginsenosides. Pxbgl converted almost all Rb3 to Rd with a productivity of 5884 μM/h, which was 346-fold higher than that of only β-xylosidase from Thermoascus aurantiacus. The productivity of Rd from the Panax ginseng root and Panax notoginseng leaf was 146 and 995 μM/h, respectively. Mutants N293 K and I447L from site-directed mutagenesis based on bioinformatics analysis showed an increase in specific activity of 29 and 7% toward Rb3, respectively. This is the first report of a β-glycosidase that can simultaneously remove four different glycosyls at the C–20 position of natural PPD-type ginsenosides and produce Rd as the sole product from P. notoginseng leaf extracts with the highest productivity.

中文翻译:


来自 Petroclostridium xylanilyticum 的多功能 β-糖苷酶通过其对 1,6-糖苷键的特异性裂解活性,更倾向于将人参皂苷 Rb3 转化为 Rd,而不是 Rb1、Rb2 和 Rc



为了通过单一酶将人参皂苷 Rb1、Rb2、Rb3 和 Rc 转化为 Rd,鉴定并使用了来自木聚糖降解细菌Petroclostridium xylanilyticum的推定 β-糖苷酶 (Pxbgl)。 Pxbgl 对 Rb3 的k cat / K m 值为 18.18 ± 0.07 mM –1 /s,显着高于 Pxbgl 对其他人参皂苷的 k cat / K m值。 Pxbgl 将几乎所有 Rb3 转化为 Rd,生产率为 5884 μM/h,比仅来自橙色嗜热子囊菌的 β-木糖苷酶高 346 倍。人参根和三七叶的 Rd 生产率分别为 146 和 995 μM/h。基于生物信息学分析的定点诱变突变体 N293 K 和 I447L 显示对 Rb3 的比活性分别增加了 29% 和 7%。这是首次报道β-糖苷酶能够同时去除天然PPD型人参皂苷C-20位上的四种不同糖基,并以最高的生产率从三七叶提取物中生产出Rd作为唯一产物。
更新日期:2024-07-25
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