Gitomer W L, Tipton K F
Biochem J. 1986 Feb 1;233(3):669-76. doi: 10.1042/bj2330669.
Histamine N-methyltransferase (EC 2.1.1.8) was purified 1100-fold from ox brain. The native enzyme has an Mr of 34800 +/- 2400 as measured by gel filtration on Sephadex G-100. The enzyme is highly specific for histamine. It does not methylate noradrenaline, adrenaline, DL-3,4-dihydroxymandelic acid, 3,4-dihydroxyphenylacetic acid, 3-hydroxytyramine or imidazole-4-acetic acid. Unlike the enzyme from rat and mouse brain, ox brain histamine N-methyltransferase did not exhibit substrate inhibition by histamine. Initial rate and product inhibition studies were consistent with an ordered steady-state mechanism with S-adenosylmethionine being the first substrate to bind to the enzyme and N-methylhistamine being the first product to dissociate.
组胺N-甲基转移酶（EC 2.1.1.8）从牛脑中纯化出来，纯化倍数为1100倍。通过在Sephadex G-100上进行凝胶过滤测定，天然酶的相对分子质量为34800±2400。该酶对组胺具有高度特异性。它不会使去甲肾上腺素、肾上腺素、DL-3,4-二羟基扁桃酸、3,4-二羟基苯乙酸、3-羟基酪胺或咪唑-4-乙酸甲基化。与来自大鼠和小鼠脑的酶不同，牛脑组胺N-甲基转移酶未表现出组胺对底物的抑制作用。初始速率和产物抑制研究与有序稳态机制一致，其中S-腺苷甲硫氨酸是第一个与酶结合的底物，N-甲基组胺是第一个从酶上解离的产物。
