In enzymology, a carnosine N-methyltransferase () is an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

that catalyzes the

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

:S-adenosyl-L-methionine + carnosine

\rightleftharpoons

S-adenosyl-L-homocysteine + anserine Thus, the two substrates of this enzyme are

S-adenosyl methionine ''S''-Adenosyl methionine (SAM), also known under the commercial names of SAMe, SAM-e, or AdoMet, is a common cosubstrate involved in methyl group transfers, transsulfuration, and aminopropylation. Although these anabolic reactions occur throug ...

and

carnosine Carnosine (''beta''-alanyl-L-histidine) is a dipeptide molecule, made up of the amino acids beta-alanine and histidine. It is highly concentrated in muscle and brain tissues. Carnosine was discovered by Russian chemist Vladimir Gulevich. Ca ...

, whereas its two

products Product may refer to: Business * Product (business), an item that serves as a solution to a specific consumer problem. * Product (project management), a deliverable or set of deliverables that contribute to a business solution Mathematics * Produ ...

are S-adenosylhomocysteine and

anserine Anserine (β-alanyl-''3''-methylhistidine) is a dipeptide containing β-alanine and 3-methylhistidine. Anserine is a derivative of carnosine, which has been methylated. Both anserine and carnosine are capable of chelating copper. Due to its m ...

. This enzyme belongs to the family of

transferase A transferase is any one of a class of enzymes that catalyse the transfer of specific functional groups (e.g. a methyl or glycosyl group) from one molecule (called the donor) to another (called the acceptor). They are involved in hundreds of di ...

s, specifically those transferring one-carbon group methyltransferases. The

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivial ...

of this enzyme class is S-adenosyl-L-methionine:carnosine N-methyltransferase. This enzyme participates in histidine metabolism.

Gene

The genes encoding carnosine ''N''-methyltransferase activity have been identified by Jakub Drozak and coworkers in 2013 and 2015. In birds and reptiles, the enzyme is encoded by histamine ''N''-methyltransferase-like gene (HNMT-like). Importantly, the HNMT-like gene is absent from available mammalian genomes and in mammalian species, the formation of anserine is catalyzed by methyltransferase that is unrelated to the reptilian and avian enzyme and encoded by C9orf41/UPF0586 gene.

Protein Nomenclature

Currently, the avian-reptilian enzyme encoded by HNMT-like gene is labeled a
carnosine ''N''-methyltransferase 2
in public databases, while the mammalian methyltransferase is name
carnosine ''N''-methyltransferase 1 (CARNMT1)

Gene

Protein Nomenclature

References

Further reading