Lin R L, Narasimhachari N
Biochim Biophys Acta. 1975 Apr 7;385(2):268-74. doi: 10.1016/0304-4165(75)90354-2.
Tetrahydrofolic acid exerts a product inhibition on the methyltetrahydrofolic acid-mediated methylation of indolethylamines. Kinetic studies showed that this inhibition was competitive with respect to methyltetrahydrofolic acid and non-competitive with respect to N-methylserotonin. Chromatographic separation of S-adenosylmethionine-dependent indolethylamine N-methyltransferase and methyltetrahydrofolic acid-dependent methyltransferase from rabbit lung was obtained. There was no cross reaction of the two enzymes to tetrahydrofolic acid, S-adenosylhomocysteine, N, N-dimethyltryptamine or bufotenin.
四氢叶酸对甲基四氢叶酸介导的吲哚乙胺甲基化具有产物抑制作用。动力学研究表明，这种抑制作用相对于甲基四氢叶酸是竞争性的，而相对于N-甲基血清素是非竞争性的。从兔肺中获得了S-腺苷甲硫氨酸依赖性吲哚乙胺N-甲基转移酶和甲基四氢叶酸依赖性甲基转移酶的色谱分离。这两种酶对四氢叶酸、S-腺苷同型半胱氨酸、N，N-二甲基色胺或蟾毒色胺没有交叉反应。
