Enzymatic synthesis of polymethylated flavonols in Chrysosplenium americanum. I. Partial purification and some properties of S-adenosyl-l-methionine: Flavonol 3-, 6-, 7-, and 4′-O-methyltransferases
作者:Vincenzo De Luca、Ragai K. Ibrahim
DOI:10.1016/0003-9861(85)90205-x
日期:1985.5
chromatofocusing, the other enzymes had apparent pI values of 4.8, 5.4, and 5.7 for the 3-, 4'-, and 6-OMTs, respectively. They had similar molecular weights (Mr 57,000) and their pH optima varied between 7.8 and 9.0, with a shift in optimal activity from lower to higher pH with increasing level of substrate methylation. Unlike the 3 and 4' enzymes, the 6-OMT showed an absolute requirement for Mg2+ whose activation
通过用硫酸铵沉淀,在Sephacryl S-200和羟基磷灰石上进行连续色谱以及在Polybuffer离子交换器上进行色谱聚焦,从美洲菊花中部分纯化了4种新的黄酮O-甲基转移酶(OMT)。他们对槲皮素的3位,3-甲基槲皮素的7位,3,7-二甲基槲皮素的4'和3,7,3'-三甲基槲皮素的6位表现出严格的位置特异性。这些酶均未与苯基丙烷,黄酮,二氢黄酮醇或其任何糖苷反应。除了7-OMT在色谱聚焦过程中失去活性外,其他酶的3-,4'-和6-OMT的pI值分别为4.8、5.4和5.7。它们具有相似的分子量(57,000先生),最适pH值在7.8至9.0之间,随着底物甲基化水平的提高,最佳活性从较低的pH值转变为较高的pH。与3和4'酶不同,6-OMT显示出对Mg2 +的绝对需求,其活化是可饱和的,并被EDTA抑制。槲皮素---- 3-甲基槲皮素---- 3,7-二甲基槲皮素---- 3,7,4'-