Some properties of phenylethanolamine-N-methyltransferase of rat brain.
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.
D000311:Adrenal Glands / Q000201:enzymology; D000818:Animals; D001921:Brain / Q000201:enzymology*; D007700:Kinetics; D008297:Male; D008970:Molecular Weight; D009647:Normetanephrine / Q000378:metabolism; D010625:Phenylethanolamine N-Methyltransferase / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D012436:S-Adenosylmethionine / Q000378:metabolism; D013379:Substrate Specificity; D013876:Thiophenes / Q000494:pharmacology
D011725:Pyridines; D013876:Thiophenes; D009647:Normetanephrine; C006214:3-methyl-1,2,3,4-tetrahydro(1)benzothieno(3,2-c)pyridine hydrochloride; D012436:S-Adenosylmethionine; D010625:Phenylethanolamine N-Methyltransferase