Nnmt, also known as Nicotinamide N-methyltransferase isoform1, is the family of transferases, specifically those transferring one-carbon group methyltransferases. It is predominantly expressed in the liver, and a lower expression is seen in the kidney, lung, skeletal muscle, placenta and heart. Nnmt catalyzes the N-methylation of nicotinamide and other pyridines to form pyridinium ions. This activity is important for biotransformation of many drugs and xenobiotic compounds. Recombinant mouse Nnmt, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.