Reaction: 2 L-ascorbate + H2O2 + 2 H+ = L-ascorbate + L-dehydroascorbate + 2 H2O (overall reaction)
(1a) 2 L-ascorbate + H2O2 + 2 H+ = 2 monodehydroascorbate + 2 H2O
(1b) 2 monodehydroascorbate = L-ascorbate + L-dehydroascorbate (spontaneous)
Glossary: monodehydroascorbate = ascorbate radical
Other name(s): L-ascorbic acid peroxidase; L-ascorbic acid-specific peroxidase; ascorbate peroxidase; ascorbic acid peroxidase
Systematic name: L-ascorbate:hydrogen-peroxide oxidoreductase
Comments: A heme protein. Oxidizes ascorbate and low molecular weight aromatic substrates. The monodehydroascorbate radical produced is either directly reduced back to ascorbate by EC 1.6.5.4 [monodehydroascorbate reductase (NADH)] or undergoes non-enzymatic disproportionation to ascorbate and dehydroascorbate.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 72906-87-7
References:
1. Shigeoka, S., Nakano, Y. and Kitaoka, S. Purification and some properties of L-ascorbic-acid-specific peroxidase in Euglena gracilis. Z. Arch. Biochem. Biophys. 201 (1980) 121-127. [PMID: 6772104]
2. Shigeoka, S., Nakano, Y. and Kitaoka, S. Metabolism of hydrogen peroxide in Euglena gracilis Z by L-ascorbic acid peroxidase. Biochem. J. 186 (1980) 377-380. [PMID: 6768357]
3. Nakano, Y and Asada, K. Purification of ascorbate peroxidase in spinach chloroplasts; its inactivation in ascorbate-depleted medium and reactivation by monodehydroascorbate radical. Plant Cell Physiol. 28 (1987) 131-140.
4. Patterson, W.R. and Poulos, T.L. Crystal structure of recombinant pea cytosolic ascorbate peroxidase. Biochemistry 34 (1995) 4331-4341. [PMID: 7703247]
5. Sharp, K.H., Moody, P.C., Brown, K.A. and Raven, E.L. Crystal structure of the ascorbate peroxidase-salicylhydroxamic acid complex. Biochemistry 43 (2004) 8644-8651. [PMID: 15236572]
6. Macdonald, I.K., Badyal, S.K., Ghamsari, L., Moody, P.C. and Raven, E.L. Interaction of ascorbate peroxidase with substrates: a mechanistic and structural analysis. Biochemistry 45 (2006) 7808-7817. [PMID: 16784232]