(HNMT) is the enzyme which catalyzes the n-methylation of histamine as follows: Histamine + S-Adenosyl methionine ------> (SAM)methyladed Histamine. The mechanism involves the transfer of an active methyl group from S-Adenosyl methionine (SAM) to histamine. Histamine is present in most of mammalian tissues and HNMT is the enzyme responsible for inactivation of histamine in mammals. Methylation is major route of histamine metabolism. HNMT has been used to measure histamine by radio-enzymatic method. HNMT has been purified from rat kidney. Molecular weight equals 33,400, pH optimum is 8.00-8.25. We have also purified it from bovine kidney which seems to be very similar to rat kidney.
Enzyme Commission Number
The amount of enzyme which will convert one nanomole of histamine to methyl histamine per hour at pH 8.5 at 37°C.
Store at -20°C (-4°F)
Histamine N-Methyl Transferase; HNMT; EC 18.104.22.168