Accepted name: L-gulonolactone oxidase
Reaction: L-gulono-1,4-lactone + O2 = L-ascorbate + H2O2 (overall reaction)
(1a) L-gulono-1,4-lactone + O2 = L-xylo-hex-2-ulono-1,4-lactone + H2O2
(1b) L-xylo-hex-2-ulono-1,4-lactone = L-ascorbate (spontaneous)
Other name(s): L-gulono-γ-lactone: O2 oxidoreductase; L-gulono-γ-lactone oxidase; L-gulono-γ-lactone:oxidoreductase; GLO
Systematic name: L-gulono-1,4-lactone:oxygen 3-oxidoreductase
Comments: A microsomal flavoprotein (FAD). The product spontaneously isomerizes to L-ascorbate. While most higher animals can synthesize asborbic acid, primates and guinea pigs cannot [3].
1.  Isherwood, F.A., Mapson, L.W. and Chen, Y.T. Synthesis of L-ascorbic acid in rat liver homogenates. Conversion of L-gulono- and L-galactono-γ-lactone and the respective acids into L-ascorbic acid. Biochem. J. 76 (1960) 157–171. [PMID: 14405898]
2.  Kiuchi, K., Noshikimi, M. and Yagi, K. Purification and characterization of L-gulonolactone oxidase from chicken kidney microsomes. Biochemistry 21 (1982) 5076–5082. [PMID: 7138847]
3.  Nishikimi, M., Fukuyama, R., Minoshima, S., Shimizu, N. and Yagi, K. Cloning and chromosomal mapping of the human nonfunctional gene for L-gulono-γ-lactone oxidase, the enzyme for L-ascorbic acid biosynthesis missing in man. J. Biol. Chem. 269 (1994) 13685–13688. [PMID: 8175804]
4.  Chatterjee, I.B., Chatterjee, G.C., Ghosh, N.C. and Guha, B.C. Identification of 2-keto-L-gulonolactone as an intermediate in the biosynthesis of L-ascorbic acid. Naturwissenschaften 46 (1959) 475.
[EC created 1965, modified 2001, modified 2006]

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