Isolation from pig lens of two proteins with dihydrodiol dehydrogenase and aldehyde reductase activities.

Dimeric and monomeric proteins containing dihydrodiol dehydrogenase and aldehyde reductase activities were purified from pig lens. The dimeric enzyme of Mr 65,000 specifically oxidized the trans-dihydrodiols of naphthalene and benzene with NADP+ as a strict cofactor, and reduced alpha-diketones, aromatic aldehydes and glyceraldehyde with NADPH as a cofactor. The monomeric enzyme of Mr 35,000, although identical with aldose reductase, oxidized the trans-dihydrodiol of naphthalene at a pH optimum of 7.6. These results suggest that the two enzymes are involved in the pathogenesis of naphthalene cataract.