Amine N-methyltransferase (), also called indolethylamine N-methyltransferase, and thioether S-methyltransferase, is an enzyme that is ubiquitously present in non-neural tissues and catalyzes the N-methylation of tryptamine and structurally related compounds. It can also catalyze the methylation of thioether and selenoether compounds, although the physiological significance of this biotransformation is not yet known.

The general reaction taking place is:

1. S-adenosyl-L-methionine + an amine S-adenosyl-L-homocysteine + a methylated amine

Function

Important reactions known to be catalysed by the enzyme include the dimethylation of tryptamine and serotonin, which are transformed to N,N-dimethyltryptamine (DMT) and bufotenine respectively, for example:

A wide range of primary, secondary and tertiary amines can act as substrates, including tryptamine, aniline, nicotine and a variety of drugs and other xenobiotics.

The enzyme can also transfer methyl groups to atoms other than nitrogen, for example sulfur and selenium.

Nomenclature

This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is S-adenosyl-L-methionine:amine N-methyltransferase. Other names in common use include nicotine N-methyltransferase, tryptamine N-methyltransferase, indolethylamine N-methyltransferase, and arylamine N-methyltransferase.

Structural studies

As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code .

References