Sprague-Dawley rat liver cytosol

• 英文名称: Sprague-Dawley rat liver cytosol

反应信息

• 作为试剂：
  描述：

  S-腺苷蛋氨酸 、 表儿茶素 在 Sprague-Dawley rat liver cytosol Tris-HCl buffer 、 magnesium chloride 、 1,4-二巯基-2,3-丁二醇 作用下， 反应 1.0h， 生成 symplocosidin 、 4’-O-Methylepicatechin 、 S-(5'-腺苷)-L-高半胱氨酸
  参考文献：
  名称：

  Rapid conversion of tea catechins to monomethylated products by rat liver cytosolic catechol-O-methyltransferase

  摘要：

  1. The metabolic O-methylation of several catechol-containing tea polyphenols by rat liver cytosolic catechol-O-methyltransferase (COMT) has been studied.2. When (-)-epicatechin was used as substrate, its O-methylation showed dependence on incubation time, cytosolic protein concentration, incubation pH and concentration of S-adenosyl-L-methionine. The O-methylation of increasing concentrations of (-)epicatechin followed typical Michaelis-Menten kinetics, and the apparent K-m and V-max were 51 muM and 2882 pmol mg protein(-1) min(-1), respectively, at pH 7.4, and were 17 muM and 2093 pmol mg protein(-1) min(-1), respectively, at pH 10.0.3. Under optimized conditions for in vitro O-methylation, (-)-epicatechin, epicatechin and (-)-epigallocatechin were rapidly O-methylated by rat liver cytosol. In comparison, (-)-epicatechin gallate and (-)-epigallocatechin gallate were O-methylated at significantly lower rates under the same reaction conditions.4. COMT-catalysed O-methylation of (-)-epicatechin and (-)-epigallocatechin was inhibited in a concentration-dependent manner by S-adenosyl-L-homocysteine, a demethylated product of S-adenosyl-L-methionine. The IC50 was similar to 10 muM.5. In summary, the results showed that several catechol-containing tea polyphenols were rapidly O-methylated by rat liver cytosolic COMT. These observations raise the possibility that some of the biological effects of tea polyphenols may be exerted by their O-methylated products or may result from their potential inhibition of the COMT-catalysed O-methylation of endogenous catecholamines and catechol oestrogens.

  DOI：

  10.1080/00498250110079798