野大豆(Glycine soja Siebold & Zucc.)是一种重要的粮油兼用作物,富含多种黄酮和黄酮糖苷,具有多种药理活性.糖基化可以将黄酮苷元转化为更稳定、生物活性更强、结构更多样的糖苷.通过基因组分析和酶挖掘,报道了一种来自野大豆的黄酮UDP-糖基转移酶GsUGT1,该酶主要作用于甘草素7-OH位置,对6种黄酮受体具有催化活性.此外,在大肠杆菌中成功异源表达GsUGT1并对其纯化,酶学性质表征发现在pH为7.0、温度为35℃时,酶的催化活性达到最大,米氏动力学研究表明GsUGT1的催化效率kcat/Km为6.70×10-5 pmol/(L·s).最后通过分子对接对GsUGT1的催化机制进行了初步探究.首次报道了野大豆来源的UDP-糖基转移酶GsUGT1,该酶有望成为酶法合成黄酮糖苷衍生物的有效工具.
Investigation and Functional Characterization of the Flavonoid UDP-glycosyltransferase GsUGT1 from Glycine soja
Wild soya(Glycine soja Siebold & Zucc.)is an important cereal and oil crop,rich in flavonoids and with a variety of pharmacological activities.Glycosylation can transform aglycones into glycosides with greater stability,stronger biological activity and more diverse structures.Through genome analysis and enzyme mining,a flavonoid UDP-glycosyltransferase GsUGT1 from wild soybean was reported,which acts mainly on the 7-OH position of liquiritigenin and has catalytic activity on 6 types of flavonoid receptors.In addition,GsUGT1 was successfully heterologously expressed in E.coli and then purified.Enzymatic characterization revealed that the catalytic activity of the enzyme was maximal at pH 7.0 and temperature 35℃.A Michaelis-Menten kinetics study showed that the catalytic efficiency kcat/Km of GsUGT1 was 6.70 × 10-5μmol/(L·S).Through molecular docking,the catalytic mechanism of GsUGT1 was preliminarily explored.To the best of our knowledge,this is the first study to report the UDP-glycosyltransferase GsUGT1 in wild soybean,which is expected to become an effective tool for the enzymatic synthesis of flavonoid glycoside derivatives.
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