(3H)methylation of various imidazole group-containing compounds catalyzed by carnosine N-methyltransferase.

The transfer of methyl group from SAM was determined with the use of homogenous recombinant chicken histamine N-methyltransferase-like protein (HNMT-like) and chicken muscle carnosine N-methyltransferase purified by chromatography on DEAE-Sepharose, Q-Sepharose, Superdex 200 and Superdex 75. Enzyme preparations were incubated for 10–15 min in the presence of 1 µM (1H+3H)SAM and 10 mM of the indicated methyl-group acceptor with the exception of histamine that was added at 0.1 mM concentration. Values are the means ± S.E. of two or three separate experiments.