Characterization of a novel thermostable glucose-tolerant GH1 β-glucosidase from the hyperthermophile Ignisphaera aggregans and its application in the efficient production of baohuoside I from icariin and total epimedium flavonoids
Characterization of a novel thermostable glucose-tolerant GH1 β-glucosidase from the hyperthermophile Ignisphaera aggregans and its application in the efficient production of baohuoside I from icariin and total epimedium flavonoids
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DOI：
10.1016/j.bioorg.2020.104296
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发表时间：
2020-11-01
影响因子：
5.1
通讯作者：
Wei, Min
中科院分区：
文献类型：
--
作者：
Xie, Jingcong;Xu, Hao;Wei, Min
从淫羊藿中提取的次要黄酮类化合物包霍苷I的生物活性优于其前体化合物淫羊藿苷和其他主要淫羊藿黄酮类化合物。本研究克隆并表达了一个新的β-葡萄糖苷酶基因（Igag_0940），以提高宝活苷I生产过程中的转化效率。首次将重组蛋白IagBgl 1纯化并鉴定为GH 1家族蛋白的三聚体。重组IagBgl 1在95 ℃、pH6.5时活性最高，90 ℃孵育4 h后活性仍保持在70%以上。IagBgl 1对淫羊藿苷有很高的催化活性，K-cat/K-m比值为488.19 mM（-1）·s（-1）。在优化条件下（65 ℃，pH6.5，0.8U/mL酶，90 min），10 g/L淫羊藿苷转化为7.564g/L宝藿苷I，摩尔转化率为99.48%。同时，以10 g/L淫羊藿总黄酮为原料，利用IagBgl 1和另外两种耐热酶构建的两步转化体系，可获得2.434 g/L的宝霍苷I。这是首次报道利用耐热酶转化法生产宝藿苷I。
The minor flavonoid baohuoside I from Herba epimedii has better bioactivities than its precursor compounds icariin and other major epimedium flavonoids. In this study, a novel beta-glucosidase gene (Igag_0940) was cloned and expressed to improve the conversion efficiency in the process of baohuoside I production. For the first time, the recombinant IagBgl1 was purified and then identified uniquely as a trimer in GH 1 family protein from Archaea. The maximum activity of recombinant IagBgl1 was exhibited at 95 degrees C, pH 6.5, and it retained more than 70% after incubation at 90 degrees C for 4 h. IagBgl1 had a high catalytic activity towards icariin with a K-cat/K-m ratio of 488.19 mM(-1).s(-1). Under optimized conditions (65 degrees C, pH 6.5, 0.8 U/mL enzyme, and 90 min), 10 g/L icariin was transformed into 7.564 g/L baohuoside I with a molar conversion of 99.48%. Meanwhile, 2.434 g/L baohuoside I was obtained from 10 g/L total epimedium flavonoids by a two-step conversion system built with IagBgl1 and two other thermostable enzymes. This is the first report of enzymatic conversion for producing baohuoside I by thermostable enzymes.