title: Occurrence of hydroxysteroid oxidoreductases in liver of turtles.
abstract: 1. Hydroxysteroid oxidoreductases have been partially purified from the cytosol fraction (105,000 g supernatant) of liver from a fresh-water turtle (Podocnemis expansa) and a sea-water turtle (Chelonia mydas mydas) by precipitation with ammonium sulphate (AS, 10-80% saturation). 2. The following enzymes were detected (substrates in brackets): 3 alpha-hydroxysteroid oxidoreductase (androsterone), 3 beta-hydroxysteroid oxidoreductase (DHEA) and 17 beta-hydroxysteroid oxidoreductase (testosterone, oestradiol-17 beta). NAD as well as NADP were effective as cofactors. 3. In fresh-water turtle, highest activities of the 3 alpha-enzyme were measured in the 20% AS fraction (cofactor NAD), of the 3 beta-enzyme in the 60% AS fraction (cofactor NAD) and of the 17 beta-enzyme in the 40% AS fraction (cofactor NADP). 4. In sea-water turtle, highest activities were observed for all three enzymes in the 60% AS fraction. 5. Generally, enzyme activities were higher in sea-water turtles than in fresh-water turtles. The most active enzyme in both turtles was found to be the 3 alpha-hydroxysteroid oxidoreductase, followed by the 17 beta- and the 3 beta-hydroxysteroid oxidoreductases.
authors.affiliation: Institut für Klinische Biochemie, Universität Bonn, FR Germany.
authors.forename: D
authors.initials: D
authors.lastname: Hamel-Jönsson
authors.forename: G H
authors.initials: GH
authors.lastname: Vieira
authors.forename: B P
authors.initials: BP
authors.lastname: Lisbôa
authors.forename: H
authors.initials: H
authors.lastname: Breuer
mesh_terms: D015067:17-Hydroxysteroid Dehydrogenases / Q000378:metabolism; D015096:3-Hydroxysteroid Dehydrogenases / Q000378:metabolism; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific); D000818:Animals; D002250:Carbon Radioisotopes; D003600:Cytosol / Q000201:enzymology; D004960:Estradiol Dehydrogenases / Q000378:metabolism; D005260:Female; D006913:Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008297:Male; D013045:Species Specificity; D014426:Turtles / Q000378:metabolism*
chemical_list: D002250:Carbon Radioisotopes; D015067:17-Hydroxysteroid Dehydrogenases; D015096:3-Hydroxysteroid Dehydrogenases; D006913:Hydroxysteroid Dehydrogenases; D045002:3-alpha-Hydroxysteroid Dehydrogenase (B-Specific); D004960:Estradiol Dehydrogenases