- Source: Adenosylhomocysteine nucleosidase
In enzymology, an adenosylhomocysteine nucleosidase (EC 3.2.2.9) is an enzyme that catalyzes the chemical reaction
S-adenosyl-L-homocysteine + H2O
⇌
{\displaystyle \rightleftharpoons }
S-(5-deoxy-D-ribos-5-yl)-L-homocysteine + adenine
Thus, the two substrates of this enzyme are S-adenosyl-L-homocysteine and H2O, whereas its two products are S-(5-deoxy-D-ribos-5-yl)-L-homocysteine 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-adenosyl-L-homocysteine homocysteinylribohydrolase. Other names in common use include S-adenosylhomocysteine hydrolase (ambiguous), S-adenosylhomocysteine nucleosidase, 5'-methyladenosine nucleosidase, S-adenosylhomocysteine/5'-methylthioadenosine nucleosidase, and AdoHcy/MTA nucleosidase. This enzyme participates in methionine metabolism.
Structural studies
As of late 2007, 8 structures have been solved for this class of enzymes, with PDB accession codes 1JYS, 1NC1, 1NC3, 1Y6Q, 1Y6R, 1Z5N, 1Z5O, and 1Z5P.
References
Duerre JA (1962). "A hydrolytic nucleosidase acting on S-adenosylhomocysteine and on 5-methylthioadenosine". J. Biol. Chem. 237 (12): 3737–3741. doi:10.1016/S0021-9258(19)84517-9.
Ferro AJ, Barrett A, Shapiro SK (1976). "Kinetic properties and the effect of substrate analogues on 5'-methylthioadenosine nucleosidase from Escherichia coli". Biochim. Biophys. Acta. 438 (2): 487–94. doi:10.1016/0005-2744(76)90264-3. PMID 782530.