EC - Adenosylhomocysteine nucleosidase

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IntEnz Enzyme Nomenclature


Accepted name:
adenosylhomocysteine nucleosidase
Other names:
5'-methyladenosine nucleosidase
S-adenosylhomocysteine hydrolase [ambiguous]
S-adenosylhomocysteine nucleosidase
S-adenosylhomocysteine/5'-methylthioadenosine nucleosidase
AdoHcy/MTA nucleosidase
Systematic name:
S-adenosyl-L-homocysteine homocysteinylribohydrolase



This enzyme, found in bacteria and plants, acts on three different substrates. It is involved in the S-adenosyl-L-methionine (SAM, AdoMet) cycle, which recycles S-adenosyl-L-homocysteine back to SAM, and in salvage pathways for 5'-deoxyadenosine and S-methyl-5'-thioadenosine, which are produced from SAM during the action of many enzymes. Cf. The plant enzyme EC

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0008782
CAS Registry Number: 9055-10-1
UniProtKB/Swiss-Prot: (194) [show] [UniProt]


  1. Duerre, J.A.
    A hydrolytic nucleosidase acting on S-adenosylhomocysteine and on 5-methylthioadenosine.
    J. Biol. Chem. 237 : 3737-3741 (1962).
  2. Ferro, A.J., Barrett, A. and Shapiro, S.K.
    Kinetic properties and the effect of substrate analogues on 5'-methylthioadenosine nucleosidase from Escherichia coli.
    Biochim. Biophys. Acta 438 : 487-494 (1976). [PMID: 782530]
  3. Cornell, K. A., Swarts, W. E., Barry, R. D., Riscoe, M. K.
    Characterization of recombinant Eschericha coli 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase: analysis of enzymatic activity and substrate specificity.
    Biochem. Biophys. Res. Commun. 228 : 724-732 (1996). [PMID: 8941345]
  4. Park, E. Y., Choi, W. S., Oh, S. I., Kim, K. N., Shin, J. S., Song, H. K.
    Biochemical and structural characterization of 5'-methylthioadenosine nucleosidases from Arabidopsis thaliana.
    Biochem. Biophys. Res. Commun. 381 : 619-624 (2009). [PMID: 19249293]
  5. Farrar, C. E., Siu, K. K., Howell, P. L., Jarrett, J. T.
    Biotin synthase exhibits burst kinetics and multiple turnovers in the absence of inhibition by products and product-related biomolecules.
    Biochemistry 49 : 9985-9996 (2010). [PMID: 20961145]
  6. North, J.A., Wildenthal, J.A., Erb, T.J., Evans, B.S., Byerly, K.M., Gerlt, J.A. and Tabita, F.R.
    A bifunctional salvage pathway for two distinct S-adenosylmethionine by-products that is widespread in bacteria, including pathogenic Escherichia coli.
    Mol. Microbiol. (2020). [PMID: 31950558]

[EC created 1972, modified 2004, modified 2020]