Studies on the Enzymic Methylation of Histamine.

Abstract

The enzymic methylation of histamine has been studied by using an essentially homogeneous preparation of histamine-N-methyl-transferase. The enzyme did not appear to be a metalloenzyme, and no cofactors related to vitamin B12 could be detected in the enzyme preparation. The transferase has SH-groups essential for its enzymic activity, and the pH-optimum of the reaction is 8.8. The influence of some histamine analogues on the reaction as well as studies on substrate specificity are described. The methyl group transfer from S-adenosyl-methionine to histamine probably occurs without a methylated enzyme as an intermediate.