Biosynthesis of gallotannins: β-Glucogallin-dependent formation of 1,2,3,4,6-pentagalloylglucose by enzymatic galloylation of 1,2,3,6-tetragalloylglucose
作者:Jessica Cammann、Klaus Denzel、Gerhard Schilling、Georg G. Gross
DOI:10.1016/0003-9861(89)90161-6
日期:1989.8
An acyltransferase was detected in young leaves of pedunculate oak (Quercus robur) that catalyzed the formation of 1,2,3,4,6-penta-O-galloyl-beta-D-glucose, the common precursor of gallotannins and the related ellagitannins. This enzyme depended on beta-glucogallin (1-O-galloyl-beta-D-glucose) as acyl donor; 1,2,3,6-tetra-O-galloyl-beta-D-glucose was specifically required as acceptor molecule, whereas
在花序栎 (Quercus robur) 的幼叶中检测到一种酰基转移酶,该酶催化 1,2,3,4,6-五-O-没食子酰-β-D-葡萄糖的形成,这是没食子单宁和相关鞣花单宁的常见前体. 这种酶依赖于β-葡萄糖没食子苷(1-O-没食子酰-β-D-葡萄糖)作为酰基供体;1,2,3,6-四-O-没食子酰基-β-D-葡萄糖作为受体分子是特别需要的,而与该底物的1,2,4,6-异构体没有发生反应。部分纯化的酶 (Mr 260,000) 在 pH 5.0 和 6.5 之间稳定;在 pH 值 6.3 和 40 摄氏度时观察到最高活性。分别确定了底物 β-葡糖没食子蛋白和四没食子酰葡萄糖的 Km 值分别为 2.3 和 1.0 mM。根据化学计量研究,系统名称“β-葡萄糖没食子苷:1,2,3,