Díaz Borges J M, Urbina M, Drujan B D
Neurochem Res. 1978 Feb;3(1):15-26. doi: 10.1007/BF00964357.
Phenylethanolamine-N-methyltransferase (PNMT, EC 2.1.1.28) was partially purified from rat brain. Brain homogenates were subjected to ultracentrifugation, salt fractionation, and gel filtration on Sephadex G-100. To compare the rat brain PNMT with that of adrenals, the same procedure was carried out with rat adrenal homogenates. The brain enzyme was eluted from Sephadex as a single fraction with a molecular weight of 26,900, while the enzyme from adrenals under the same conditions appeared in two fractions with molecular weights of 38,700 and 108,500. The brain fraction separated on Sephadex G-100 was active on phenylethanolamine substrates and inactive on indoleamine and phenylethylamine substrates. Products of the enzyme reaction were identified by bidimensional thin-layer chromatography as N-methyl derivatives of the corresponding amines. Kinetic studies showed that the type of inhibition of PNMT from rat brain and rat adrenals by SK&F 7698 was the same as described for PNMT from rabbit adrenals. Also, when normetanephrine and S-adenosyl-L-methionine were used as substrates, the apparent Km values found with PNMT from rat adrenals and rat brain were similar.
从大鼠脑中部分纯化了苯乙醇胺 -N-甲基转移酶（PNMT，EC 2.1.1.28）。脑匀浆经过超速离心、盐分级分离以及在葡聚糖凝胶G - 100上的凝胶过滤。为了将大鼠脑PNMT与肾上腺的进行比较，对大鼠肾上腺匀浆进行了相同的操作。脑酶在葡聚糖凝胶上以单一馏分洗脱，分子量为26,900，而在相同条件下肾上腺的酶以分子量分别为38,700和108,500的两个馏分出现。在葡聚糖凝胶G - 100上分离的脑馏分对苯乙醇胺底物有活性，而对吲哚胺和苯乙胺底物无活性。酶反应产物通过双向薄层色谱法鉴定为相应胺的N - 甲基衍生物。动力学研究表明，SK&F 7698对大鼠脑和大鼠肾上腺PNMT的抑制类型与对兔肾上腺PNMT描述的相同。此外，当去甲变肾上腺素和S - 腺苷 -L-蛋氨酸用作底物时，大鼠肾上腺和大鼠脑PNMT的表观Km值相似。
