depending upon the positions of the hydroxyl groups. Quercetin, as an example of a flavonol, was rapidly sulfated when p-nitrophenyl sulfate (PNS) was taken as a donor substrate. At a ten-fold molar excess of PNS over quercetin, two products, the 3,3'-disulfate and 3,3',7-trisulfate derivatives, were formed, but the 4'- and 5-hydroxyl groups were not sulfated. In the case of equimolar or two-fold molar excess
从人的肠道细菌中部分纯化了一种新型的芳基磺基转移酶,并对其酶学性质进行了研究。尽管
硫酸化活性随羟基的位置而变化,但发现多
酚(如
查尔酮,
黄酮和类
黄酮)被细菌的芳基磺基转移酶
硫酸化。当以对
硝基苯基
硫酸盐(
PNS)作为供体底物时,作为
黄酮醇实例的
槲皮素被快速
硫酸化。在
PNS超过
槲皮素10倍摩尔过量的情况下,形成了3,3'-二
硫酸盐和3,3',7-三
硫酸盐衍
生物两种产物,但4'-和5-羟基未被
硫酸化。在
PNS与
槲皮素等摩尔或两倍摩尔过量的情况下,仅生成3,3'-二
硫酸盐,而未形成单
硫酸盐。