Abstract

EFFICIENT GLYCOSYLATION OF COUMARIN BY PLANT GLYCOSYLTRANSFERASE UGT74AN3

Si-Si Li, Wei Xu, Fo-Lan Lin, Qi-Qi Wang and Ren-Wang Jiang*

ABSTRACT

The glycosyltransferase UGT74AN3 derived from the plant Catharanthus roseus was cloned, expressed and purified. The purified enzyme was used as the catalyst and 4-methyl-7-mercaptocoumarin was selected as the substrate. In the presence of sugar donor, UGT74AN3 could transfer the activated sugar group to the substrate. The chemical structure of the glycosylation product was determined by HR-ESI-MS, NMR and single crystal X-ray diffraction. The reaction conditions (pH 7.0, 37 ℃, 12 h, divalent metal ion Mn2+ or Co2+) were optimized to maximize the yield. The results showed that UGT74AN3 could convert 4-methyl-7-mercaptocoumarin to the corresponding glycoside. Furthermore, the enzyme was proven for the first time that it could catalyze the formation of S-glycosidic bond. The result from this study is beneficial to the structural modification of coumarins by enzymatic method.

Keywords: Glycosyltransferase, UGT74AN3, Coumarin.