Alpha-methylhistamine methylation by histamine methyltransferase.
Enzymatic methylation of histamine and analogues by histamine methyltransferase (HMT) was studied. Incubation of histamine or alpha-methylhistamine with HMT and S-adenosylmethionine was shown by GC-MS to yield tele-methyl and alpha-methyl-tele-methyl-histamine, respectively. Kinetic analysis of the reactions indicated that both substrates exhibited equivalent Vmax values, but that histamine's Km was ten-fold lower than that of alpha-methylhistamine. These results indicate that alpha-methylhistamine can be methylated as effectively as histamine, and may be a useful tool in further studies of HMT.
D000818:Animals; D008401:Gas Chromatography-Mass Spectrometry; D006632:Histamine / Q000378:metabolism; D006637:Histamine N-Methyltransferase / Q000494:pharmacology*; D007700:Kinetics; D008745:Methylation; D008761:Methylhistamines / Q000378:metabolism*; D008780:Methyltransferases / Q000494:pharmacology*; D051381:Rats
D008761:Methylhistamines; D006632:Histamine; D008780:Methyltransferases; D006637:Histamine N-Methyltransferase