N-Methylarginine (NMMA)

-Methylarginine ((2S)-2-Amino-5-[(N′-methylcarbamimidoyl)amino]pentanoic acid) is an inhibitor of nitric oxide synthase. Chemically, it is a methyl derivative of the amino acid arginine. It is used as a biochemical tool in the study of physiological role of nitric oxide.

Methylation of arginine residues in proteins is increasingly recognised as an important post-translational modification (PTM). The reaction is catalysed by a family of protein arginine methyltransferases (PRMTs) that methylate the guanidine nitrogens of arginine. Two broad families of PRMTs have been described / type I that generates asymmetric dimethylarginine (ADMA) and type II that generates symmetric dimethylarginine (SDMA). Both types of PRMTs can also generate monomethyl arginine (LNMMA), probably as an intermediate en route to dimethylation.