7 methylxanthosine synthase

In enzymology, a 7-methylxanthosine synthase (EC 2.1.1.158) is an enzyme that catalyzes the chemical reaction

S-adenosyl-L-methionine + xanthosine ⇌ S-adenosyl-L-homocysteine + 7-methylxanthosine

Thus, the two substrates of this enzyme are S-adenosyl methionine and xanthosine, whereas its two products are S-adenosylhomocysteine and 7-methylxanthosine.

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:xanthosine N7-methyltransferase. Other names in common use include xanthosine methyltransferase, XMT, xanthosine:S-adenosyl-L-methionine methyltransferase, CtCS1, CmXRS1, CaXMT1, and S-adenosyl-L-methionine:xanthosine 7-N-methyltransferase.