Aldonolactone oxidoreductases catalyzing the terminal step in the biosynthesis of ascorbate or its analogues in (a) plants, animals, protozoa and bacteria, (b) Penicillia and (c) yeast from their preferred substrates. ALO, d-arabinono-1,4-lactone oxidase; GalLO, l-galactono-1,4-lactone oxidase; GLDH, l-galactono-1,4-lactone dehydrogenase; GulLDH, l-gulono-1,4-lactone dehydrogenase; GulLO, l-gulono-1,4-lactone oxidase; GUO, d-gluconolactone oxidase.