N-methyltransferase that mediates the formation of anserine (beta-alanyl-N(Pi)-methyl-L-histidine) from carnosine. Anserine, a methylated derivative of carnosine (beta-alanyl-L-histidine), is an abundant constituent of vertebrate skeletal muscles. carnosine + S-adenosyl-L-methionine = anserine + H(+) + S-adenosyl-L-homocysteine kcat is 0.034 sec(-1) for carnosine. kcat is 0.519 sec(-1) for S-adenosyl-L-methionine. Monomer. Two different proteins belonging to two different protein families are able to mediate carnosine N-methyltransferase activity in chicken. This protein, which is not conserved in mammals, and another protein (AC F1N9S8), which is conserved from human to yeast. Belongs to the class I-like SAM-binding methyltransferase superfamily. HNMT family.