L-galactonolactone dehydrogenase (, 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 two chemical reactions
The first stage is the final step in the biosynthesis of vitamin C in plants and other photosynthetic eukaryotes.