쥐 뇌의 histamine N-methyltransferase(HMT)는 $(NH_4)_2SO_4$ 분류법, DEAE-셀루로즈 크로마토그래피, hydroxylapatite 크로마토그래피와 Sephadex G-75에 대한 젤 여과법으로 정제되었다. 전체 정제는 8%의 회수율로 280배 정제되었다. HMT 활성도는 $[^{14}CH_3]$-S-adenosylmethionine(SAM)에 의한 방사성 동위원소법으로 결정하였다. 방사성 SAM은 $[^{14}CH_3]$ methionine을 가지고 쥐 간의 SAM synthetase에 의하여 합성하였다. 준비된 HMT의 specific actitity는 pH8.5에서 3.9nmol/min/mg protein이다. Histamine과 SAM에 대한 $K_m$값은 각각 $12{mu}M$과 $40{mu}M$이다. 효소활성에 대한 몇 가지의 변형시약을 검토했을 때 p-chloromercuribenzoate와 N-ethyl maleimide는 활성도를 감소시켰고 iodoacetic acid, iodoacetamide와 succinic anhydride는 효소의 활성도를 증가시킴이 관찰되었다.
Histamine-N-Methyltransferase (HMT: E.C. 2.1.1.8) was purified by the methods of ammonium sulfate fractionation, DEAE-cellulose chromatography, hydroxylapatite chromatography, and gel filtration on Sephadex G-75. Overall purification was 280-fold with a recovery of 8%. The activity of HMT was determined by radioisotopic method with $[^{14}CH_3]$S-adenosylmethionine(SAM). The labelled SAM was prepared by rat liver SAM synthetase with $[^{14}CH_3]$-methionine. The specific activity of prepared HMT was 3.9 nmol/min/mg protein at pH 8.5. The $K_m$ values of histamine and SAM were $12{mu}M$ and $40{mu}M$, respectively. It was also examined the effects of some modification reagents on the enzyme activity. p-Chloromercuribenzoate and N-ethylmaleimide inhibited the enzyme activity, while iodoacetic acid, iodoacetamide and succinic anhydride activated the enzyme activity.
