Galactonolactone dehydrogenase

L-galactonolactone dehydrogenase (EC 1.3.2.3, 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. This enzyme catalyses the following chemical reaction

(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 higher plants and in nearly all higher animals, except for primates and some birds.