Nicotinamide N-methyltransferase (NNMT) catalyzes the N-methylation of nicotinamide and
other pyridines. Human liver NNMT activity has a bimodal frequency distribution, an
observation which raises the possibility that this enzyme activity might be regulated by a
genetic polymorphism, a polymorphism that could have functional implications for individual
differences in drug and xenobiotic toxicity. As a first step toward testing that hypothesis, we
set out to clone and express a cDNA for human liver NNMT. Human liver NNMT was partially …