Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry, National Engineering Lab. for Biomass Chemical Utilization, Key and Open Lab of Forest Chemical Engineering, SFA, Key Lab of Biomass Energy Sources and Materials, Nanjing 210042, China; Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, China.
Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry, National Engineering Lab. for Biomass Chemical Utilization, Key and Open Lab of Forest Chemical Engineering, SFA, Key Lab of Biomass Energy Sources and Materials, Nanjing 210042, China; Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, China.
Bioorg Chem. 2020 Nov;104:104296. doi: 10.1016/j.bioorg.2020.104296. Epub 2020 Sep 19.
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 β-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 °C, pH 6.5, and it retained more than 70% after incubation at 90 °C for 4 h. IagBgl1 had a high catalytic activity towards icariin with a K/K ratio of 488.19 mM·s. Under optimized conditions (65 °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.
从淫羊藿中提取的微量类黄酮宝藿苷 I 比其前体化合物淫羊藿苷和其他主要的淫羊藿类黄酮具有更好的生物活性。在这项研究中，克隆并表达了一种新型的β-葡萄糖苷酶基因（Igag_0940），以提高宝藿苷 I 生产过程中的转化效率。首次从古菌 GH1 家族蛋白中纯化并鉴定出重组 IagBgl1 是一种三聚体。重组 IagBgl1 的最大活性在 95°C、pH6.5 下表现出来，在 90°C 孵育 4 小时后保留超过 70%的活性。IagBgl1 对淫羊藿苷具有很高的催化活性，K/K 值为 488.19 mM·s。在优化条件（65°C、pH6.5、0.8 U/mL 酶、90 分钟）下，10 g/L 的淫羊藿苷转化为 7.564 g/L 的宝藿苷 I，摩尔转化率为 99.48%。同时，通过构建由 IagBgl1 和另外两种耐热酶组成的两步转化系统，从 10 g/L 总淫羊藿类黄酮中获得了 2.434 g/L 的宝藿苷 I。这是首次报道利用耐热酶酶促转化生产宝藿苷 I。
