Dihydrodiol dehydrogenase activities of rabbit liver are associated with hydroxysteroid dehydrogenases and aldo-keto reductases.
1. Dihydrodiol dehydrogenase activities were investigated in rabbit liver. Using a five-step purification scheme, eight isoenzymes of dihydrodiol dehydrogenase with isoelectric points of 5.55-9.3 and promoter molecular masses of 34-35 kDa were purified to apparent homogeneity and designated CF-1 to CF-6, CM-1 and CM-2. 2. CF-1 and CF-2 had near-neutral isoelectric points of 7.4 and 6.8 and molecular masses of about 125 kDa in the native state. Both enzymes readily accepted NAD+ as well as NADP+ as coenzymes, had relatively low Km values of 0.33 mM and 0.47 mM for benzene dihydrodiol and resembled previously described carbonyl reductases in their substrate specificity towards ketones and quinones. 3. CF-5 and CF-6 had acidic isoelectric points of 5.9 and 5.55 and native molecular masses of approximately 60 kDa. They displayed a strong preference for NADP(H) as coenzyme and had high Km and Vmax with benzene dihydrodiol. Since these enzymes reduced p-nitrobenzaldehyde and glucuronic acid efficiently, they appeared to be closely related to aldehyde reductase. 4. CF-4 had a high 3 alpha-hydroxysteroid dehydrogenase activity for the diagnostic substrate androsterone, a moderate activity for other 3 alpha-hydroxysteroids as well as 17 alpha-hydroxysteroids, and relatively low activities for 3 beta-hydroxysteroids and 17 beta-hydroxysteroids. CF-5 and CM-1 had high 17 beta-hydroxysteroid dehydrogenase activity for the diagnostic substrate 5 alpha-dihydrotestosterone, and low to moderate activities for other 17 beta-hydroxysteroids as well as 3 alpha-hydroxysteroids. 5. The isoenzyme CM-2 had an isoelectric point of 9.3 and was a very active quinone reductase with phenanthrene-9,10-quinone as substrate. It was potently inhibited by phenobarbital. 6. We conclude that the dihydrodiol dehydrogenase activities of rabbit liver are associated with aldehyde and carbonyl reductase and with 3 alpha-hydroxysteroid and 17 beta-hydroxysteroid dehydrogenases.
Klein
J
J
Institute of Toxicology, University of Mainz, Federal Republic of Germany.
Thomas
H
H
Post
K
K
Wörner
W
W
Oesch
F
F
D000429:Alcohol Oxidoreductases / Q000302:isolation & purification / Q000378:metabolism*; D000449:Aldehyde Reductase; D000074408:Aldo-Keto Reductases; D000818:Animals; D000911:Antibodies, Monoclonal; D002384:Catalysis; D004591:Electrophoresis, Polyacrylamide Gel; D006913:Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D007526:Isoelectric Point; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D008297:Male; D008970:Molecular Weight; D010088:Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; D011817:Rabbits; D013379:Substrate Specificity; D014018:Tissue Distribution
D000911:Antibodies, Monoclonal; D007527:Isoenzymes; D010088:Oxidoreductases; D000429:Alcohol Oxidoreductases; D006913:Hydroxysteroid Dehydrogenases; C023125:dihydrodiol dehydrogenases; D000074408:Aldo-Keto Reductases; D000449:Aldehyde Reductase; D044925:Oxidoreductases Acting on CH-CH Group Donors; C116788:cis-1,2-dihydro-1,2-dihydroxynaphthalene dehydrogenase