Properties of the multiple forms of the soluble 17alpha-hydroxy steroid dehydrogenase of rabbit liver.
The six forms of the 17alpha-hydroxy steroid dehydrogenase purified from rabbit liver cytosol have very similar physical properties. The molecular weights of all the enzymes were within 3% of the average mol.wt of 39 600. Only one of the six enzymes showed a significant difference in amino acid composition. All but one form of the 17alpha-hydroxy steroid dehydrogenases exhibited greater activities towards the androgen, epitestosterone, than towards oestrogen substrates. With oestrogen substrates one enzyme displayed a high specificity towards the substrate oestradiol-17alpha 3-glucuronide. This high activity was lost if the glucuronic acid moiety was removed or replaced by glucose or galacturonic acid. The other enzyme forms had approximately equal activity toward oestradiol-17alpha and its glucuronide or glucoside derivative. However, substitution of galacturonic acid at C-3 of oestradiol-17alpha substantially decreased the activity of all but one enzyme form.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D004845:Epitestosterone; D004958:Estradiol / Q000031:analogs & derivatives; D004960:Estradiol Dehydrogenases / Q000032:analysis* / Q000378:metabolism; D005960:Glucosides; D006027:Glycosides; D006913:Hydroxysteroid Dehydrogenases / Q000032:analysis*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008970:Molecular Weight
D000596:Amino Acids; D005960:Glucosides; D006027:Glycosides; D004845:Epitestosterone; D004958:Estradiol; D006913:Hydroxysteroid Dehydrogenases; D004960:Estradiol Dehydrogenases