In enzymology, a methylthioadenosine nucleosidase () is an enzyme that catalyzes the chemical reaction S-methyl-5'-thioadenosine + H2O S-methyl-5-thio-D-ribose + adenine Thus, the two substrates of this enzyme are S-methyl-5'-thioadenosine and H2O, whereas its two products are S-methyl-5-thio-D-ribose and adenine. This enzyme belongs to the family of hydrolases, specifically those glycosylases that hydrolyse N-glycosyl compounds. The systematic name of this enzyme class is S-methyl-5'-thioadenosine adeninehyrolase. Other names in common use include 5'-methylthioadenosine nucleosidase, MTA nucleosidase, MeSAdo nucleosidase, and methylthioadenosine methylthioribohydrolase. This enzyme participates in urea cycle and metabolism of amino groups and methionine metabolism. Structural studies As of late 2007, 6 structures have been solved for this class of enzymes, with PDB accession codes , , , , , and . References EC 3.2.2 Enzymes of known structure