基于右旋糖酐蔗糖酶转糖基作用的槲皮素葡萄糖苷的合成研究

右旋糖酐蔗糖酶是一种以蔗糖为唯一底物，将蔗糖分子中D-葡萄糖基催化转移到受体分子上的葡萄糖基转移酶。利用右旋糖酐蔗糖酶的转糖基作用，以蔗糖为葡萄糖糖基供体，槲皮素为糖基受体，对槲皮素糖苷的酶法合成进行了探索。通过对该酶催化反应体系、催化反应条件及产物分析的研究，结果表明：在25℃下，右旋糖酐蔗糖酶能够在30％DMSO-70％乙酸-乙酸钙（0.02 mol/L，pH值5.4）的反应体系中催化合成一种槲皮素葡萄糖苷，在这个反应体系下，以10％的蔗糖作为糖基供体，槲皮素为糖基受体，右旋糖酐蔗糖酶活力为40 U/mL，转速为150 r/min，槲皮素糖苷的转化率最高，可达39.5％。通过质谱分析确定是一种槲皮素单糖苷，分子量为464。该研究结果为黄酮类物质的糖基化修饰奠定了基础。

Study on synthesis of quercetin glucoside based on transglycosylation of dextransucrase

Dextransucrase is a glucosyltransferases catalyzed by transferring D-glucopyranosyl units in sucrose to the receptor molecule to synthesize a-glucan or oligosaccharides.This paper explored the synthesis of quercetin glycoside by using sucrose as glucose glycosyl donor, quercetin as glycosyl receptor and applying the transglycosylation of dextransucrase.Enzymatic glucosylation in aqueous-organic solvents, the conditions of catalytic reaction and the structure of the product were also studied.The result showed that a new quercetin glycoside was achieved after reaction catalyzed by dextransucrase in a mixture of DMSO （ 30%） /Acetic acid calcium acetate buffer （70%）（0.02 mol/L,pH=5.4）at the 25℃.Under this reaction system, using 10%of sucrose as glucose glycosyl donor, quercetin as glucose glycosyl receptor and 40 U/mL dextransucrase, the stirring speed at 150 r/min, the conversion of quercetin glycoside could be high, up to 39.5%.The product was characterized by MS and confirmed as a quercetin mono-glycoside, and the molecular weight of the product is 464.The results of this study lays a foundation for the glycosylation of flavonoids.