Galactonolactone dehydrogenase

L-galactonolactone dehydrogenase (EC, galactonolactone dehydrogenase, L-galactono-gamma-lactone dehydrogenase, L-galactono-gamma-lactone:ferricytochrome-c oxidoreductase, GLDHase, GLDase) is an enzyme with systematic name L-galactono-1,4-lactone:ferricytochrome-c oxidoreductase.[1][2][3][4][5] This enzyme catalyses the following chemical reaction

L-galactonolactone dehydrogenase
EC number1.3.2.3
CAS number2603847
IntEnzIntEnz view
ExPASyNiceZyme view
MetaCycmetabolic pathway
PDB structuresRCSB PDB PDBe PDBsum
(1) L-galactono-1,4-lactone + 2 ferricytochrome c L-ascorbate + 2 ferrocytochrome c + 2 H+
(2) L-ascorbate + 2 ferricytochrome c L-dehydroascorbate + 2 ferrocytochrome c + 2 H+ (spontaneous)

This enzyme catalyses the final step in the biosynthesis of L-ascorbic acid in plants and other photosynthetic eukaryotes.[6]


  1. ^ Mapson, L.W.; Breslow, E. (1957). "Properties of partially purified L-galactono-γ-lactone dehydrogenase". Biochem. J. 65: 29.
  2. ^ Mapson LW, Isherwood FA, Chen YT (January 1954). "Biological synthesis of L-ascorbic acid: the conversion of L-galactono-gamma-lactone into L-ascorbic acid by plant mitochondria". The Biochemical Journal. 56 (1): 21–8. doi:10.1042/bj0560021. PMC 1269564. PMID 13126087.
  3. ^ Isherwood FA, Chen YT, Mapson LW (January 1954). "Synthesis of L-ascorbic acid in plants and animals". The Biochemical Journal. 56 (1): 1–15. doi:10.1042/bj0560001. PMC 1269562. PMID 13126085.
  4. ^ Oba K, Ishikawa S, Nishikawa M, Mizuno H, Yamamoto T (January 1995). "Purification and properties of L-galactono-gamma-lactone dehydrogenase, a key enzyme for ascorbic acid biosynthesis, from sweet potato roots". Journal of Biochemistry. 117 (1): 120–4. doi:10.1093/oxfordjournals.jbchem.a124697. PMID 7775377.
  5. ^ Ostergaard J, Persiau G, Davey MW, Bauw G, Van Montagu M (November 1997). "Isolation of a cDNA coding for L-galactono-gamma-lactone dehydrogenase, an enzyme involved in the biosynthesis of ascorbic acid in plants. Purification, characterization, cDNA cloning, and expression in yeast". The Journal of Biological Chemistry. 272 (48): 30009–16. doi:10.1074/jbc.272.48.30009. PMID 9374475.
  6. ^ Wheeler G, Ishikawa T, Pornsaksit V, Smirnoff N (March 2015). "Evolution of alternative biosynthetic pathways for vitamin C following plastid acquisition in photosynthetic eukaryotes". eLife. 4. doi:10.7554/eLife.06369. PMC 4396506. PMID 25768426.

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