Purification and kinetic properties of ox brain histamine N-methyltransferase.
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.
W L
WL
Gitomer
K F
KF
Tipton
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002417:Cattle; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D006632:Histamine / Q000378:metabolism; D006637:Histamine N-Methyltransferase / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008761:Methylhistamines / Q000494:pharmacology; D008780:Methyltransferases / Q000378:metabolism*; D051381:Rats; D012435:S-Adenosylhomocysteine / Q000494:pharmacology
D008761:Methylhistamines; C031205:3-methylhistamine; D006632:Histamine; D012435:S-Adenosylhomocysteine; D008780:Methyltransferases; D006637:Histamine N-Methyltransferase