肝脏微粒体组分对酪胺葡糖醛酸苷的生物合成。
The biosynthesis of tyramine glucuronide by liver microsomal fractions.
作者信息
Wong K P
出版信息
Biochem J. 1977 Jun 15;164(3):529-31. doi: 10.1042/bj1640529.
Labelled tyramine glucuronide was synthesized in vitro from UDP-[14C]glucuronic acid, [14C]tyramine or [3H]tyramine. The glucuronidation was carried out at pH9.2 in the presence of a monoamine oxidase inhibitor, trans-2-phenylcyclopropylamine. The Km values for tyramine were 69 and 125 micrometer and those for UDP-glucuronic acid were 260 and 290 micrometer respectively for guinea-pig and rat liver microsomal preparatons. The specific activities of microsomal glucuronyltransferase measured in fresh hepatic preparations of guinea pig, mouse and rat were respectively 601, 251 and 235 pmol of [14C]tyramine glucuronide/min per mg of protein. Increase in activity ranged from 2- to 6-fold in preparations which were frozen and thawed once and 5.4- to 10-fold when the freezing and thawing was repeated. Rabbit liver has very low activity, and monkey liver and intestine were completely devoid of this conjugating capacity.
标记的酪胺葡糖醛酸是在体外由UDP-[14C]葡糖醛酸、[14C]酪胺或[3H]酪胺合成的。葡糖醛酸化反应在pH9.2条件下，于单胺氧化酶抑制剂反式-2-苯基环丙胺存在时进行。对于豚鼠和大鼠肝脏微粒体制剂，酪胺的Km值分别为69和125微摩尔，UDP-葡糖醛酸的Km值分别为260和290微摩尔。在豚鼠、小鼠和大鼠新鲜肝脏制剂中测得的微粒体葡糖醛酸基转移酶的比活性分别为每毫克蛋白质每分钟601、251和235皮摩尔的[14C]酪胺葡糖醛酸。在冻融一次的制剂中，活性增加2至6倍，当重复冻融时，活性增加5.4至10倍。兔肝脏活性非常低，猴肝脏和肠道则完全没有这种结合能力。
Zotero 插件