IUBMB Enzyme Nomenclature


Accepted name: nucleoside oxidase

Reaction: inosine + O2 = 9-riburonosylhypoxanthine + 2 H2O
(1a) 2 inosine + O2 = 2 5'-dehydroinosine + 2 H2O
(1b) 2 5'-dehydroinosine + O2 = 2 9-riburonosylhypoxanthine

Systematic name: nucleoside:oxygen 5'-oxidoreductase

Comments: Other purine and pyrimidine nucleosides (as well as 2'-deoxyribonucleosides) are substrates, but ribose and nucleotides are not substrates. The overall reaction takes place in two separate steps, with the 5'-dehydro nucleoside being released from the enzyme to serve as substrate for the second reaction. This enzyme differs from EC, nucleoside oxidase (H2O2-forming), as it produces water rather than hydrogen peroxide.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:


1. Isono, Y., Sudo, T. and Hoshino, M. Purification and reaction of a new enzyme, nucleoside oxidase. Agric. Biol. Chem. 53 (1989) 1663-1669.

2. Isono, Y., Sudo, T. and Hoshino, M. Properties of a new enzyme, nucleoside oxidase, from Pseudomonas maltophilia LB-86. Agric. Biol. Chem. 53 (1989) 1671-1677.

[EC created 1992, modified 2001]

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