Nmetyylitransferaasin

Nmetyylitransferaasin, commonly referred to as an N-methyltransferase, is a class of enzymes that catalyze the transfer of a methyl group from the methyl donor S-adenosyl-L-methionine (SAM) to a nitrogen atom on an acceptor molecule. This methylation generates an N-methylated product and S-adenosyl-L-homocysteine (SAH). N-methyltransferases act on a wide range of substrates, including small molecules, nucleic acids, and proteins, and they play roles in metabolism, detoxification, and biosynthesis.

The reaction mechanism typically involves an SN2-like methyl transfer within a conserved active site. Most enzymes in this family belong to methyltransferase superfamilies that share structural folds and characteristic sequence motifs. SAM is the universal cofactor, and SAH is the common byproduct, which can act as an inhibitor if it accumulates.

Notable examples include glycine N-methyltransferase (GNMT), which methylates glycine to sarcosine in the liver and influences one-carbon metabolism, and nicotinamide N-methyltransferase (NNMT), which methylates nicotinamide in liver and adipose tissue and has been studied in metabolic regulation and cancer. In plants and microbes, various N-methyltransferases contribute to the biosynthesis of alkaloids and other secondary metabolites.

Biologically, N-methyltransferases impact metabolite balance, detoxification pathways, and, in some systems, regulation of protein function or gene expression through methylation. Dysregulation of certain N-methyltransferases has been associated with human diseases, and inhibitors or modulators are explored for therapeutic potential. The enzyme class is categorized under the transferases, specifically the methyltransferases (EC 2.1.1.x) family.