Showing papers on "Hydroxysteroid dehydrogenase published in 1982"
TL;DR: A gram-positive, anaerobic, chain-forming, rod-shaped anaerobe (isolate G20-7) was isolated from normal human feces and identified by cellular morphology as well as fermentative and biochemical data as Eubacterium aerofaciens.
Abstract: A gram-positive, anaerobic, chain-forming, rod-shaped anaerobe (isolate G20-7) was isolated from normal human feces. This organism was identified by cellular morphology as well as fermentative and biochemical data as Eubacterium aerofaciens. When isolate G20-7 was grown in the presence of Bacteroides fragilis or Escherichia coli (or another 7 alpha-hydroxysteroid dehydrogenase producer) and chenodeoxycholic acid, ursodeoxycholic acid produced. Time course curves revealed that 3 alpha-hydroxy-7-keto-5 beta-cholanoic acid produced by B. fragilis or E. coli or introduced into the medium as a pure substance was reduced by G20-7 specifically to ursodeoxycholic acid. The addition of glycine- and taurine-conjugated primary bile acids (chenodeoxycholic and cholic acids) and other bile acids to binary cultures of B. fragilis and G20-7 revealed that (i) both conjugates were hydrolyzed to give free bile acids, (ii) ursocholic acid (3 alpha, 7 beta, 12 alpha-trihydroxy-5 beta-cholanoic acid) was produced when conjugated (or free) cholic acid was the substrate, and (iii) the epimerization reaction was at least partially reversible. Corroborating these observations, an NADP-dependent 7 beta-hydroxysteroid dehydrogenase (reacting specifically with 7 beta-OH-groups) was demonstrated in cell-free preparations of isolate G20-7; production of the enzyme was optimal at between 12 and 18 h of growth. This enzyme, when measured in the oxidative direction, was active with ursodeoxycholic acid, ursocholic acid, and the taurine conjugate of ursodeoxycholic acid (but not with chenodeoxycholic, deoxycholic, or cholic acids) and displayed an optimal pH range of 9.8 to 10.2
81 citations
TL;DR: Both llβ-hydroxysteroid dehydrogenase activity and the cortisol to cortisone ratios were similar in the three groups of tissues, suggesting that there are no changes in placental corticosteroid metabolism in relation to parturition.
Abstract: llβ-Hydroxysteroid dehydrogenase (E.C. 1.1.1.146) activity and endogenous cortisol and cortisone concentrations were measured in samples of human placenta obtained at term: at elective cesarean section, after labor of spontaneous onset, and after labor of induced onset. Both llβ-hydroxysteroid dehydrogenase activity and the cortisol to cortisone ratios were similar in the three groups of tissues, suggesting that there are no changes in placental corticosteroid metabolism in relation to parturition. (J Clin Endocrinol Metab 54: 1251, 1982)
21 citations
TL;DR: The activity of 17 beta-hydroxysteroid dehydrogenase has been investigated in human subcutaneous adipose tissue using oestrone as substrate, oestradiol formation was linear with time and the concentration of protein in the tissue homogenate.
16 citations
TL;DR: Inhibition of 20 alpha-HSD activity by steroids was demonstrable at pH 8.8, and Androstenedione was by far the most potent inhibitor, followed by progesterone and 17 alpha-hydroxyprogesterone, Compound S and 20 beta-OH-P.
15 citations
TL;DR: The activity of 17 beta-hydroxysteroid dehydrogenase was higher at a higher concentration of E2 and was also higher in mouse than in rat blastocysts and in the mouse, the activity was higher in Day 5 than Day 4 blastocytes during the first day in culture.
Abstract: When Day 5 rat blastocysts and Day 4 and 5 mouse blastocysts were cultured in 53 microliters of medium containing 1340 or 2680 pg [3H]estradiol (E2), large amounts of [3H]estrone (E1) were detected in the medium at daily intervals for up to 5 days. This indicates the presence of 17 beta-hydroxysteroid dehydrogenase in the embryos. The activity was higher at a higher concentration of E2 and was also higher in mouse than in rat blastocysts. In the mouse, the activity was higher in Day 5 than Day 4 blastocysts during the first day in culture; then it decreased in Day 5 but increased in Day 4 blastocysts. The importance of E2 in embryonic development and implantation as suggested by others may be related to the activity of 17 beta-hydroxysteroid dehydrogenase.
13 citations
TL;DR: Four forms of this 3(17) alpha-hydroxysteroid dehydrogenase were resolved by a purification procedure which included DEAE-cellulose chromatography and isoelectric focusing and three of the isolated enzymes were homogeneous on the basis of polyacrylamide gel electrophoresis.
9 citations
TL;DR: Enzyme activity was demonstrable throughout the excurrent ducts of the hamster and marmoset, with maximal staining occurring in the middle segment of the epididymis in both species, the region of maximum activity of hydroxysteroid dehydrogenase is where spermatozoa first develop their fertilizing capacity.
Abstract: The presence and distribution of delta 5-3 beta-hydroxysteroid dehydrogenase (delta 5-3 beta-HSD: EC 1.1.1.51) and 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD: EC 1.1.1.51) were studied histochemically in the excurrent ducts of the rabbit, hamster and marmoset monkey. Dehydroepiandrosterone (DHEA) and testosterone were used as substrates for delta 5-3 beta-HSD and 17 beta-HSD respectively, while phenanthroline monohydrate was used to eliminate non-specific staining due to other tissue dehydrogenases. The rabbit possessed least enzyme activity, which was confined to tubules in the middle segment of the epididymis. Enzyme activity was demonstrable throughout the excurrent ducts of the hamster and marmoset, with maximal staining occurring in the middle segment of the epididymis in both species. The region of maximum activity of hydroxysteroid dehydrogenase is where spermatozoa first develop their fertilizing capacity.
9 citations
TL;DR: The results suggest that prostaglandins can have a direct, dose-dependent effect on the isolated human placental 20 alpha-HSDH without cyclic nucleotides as intermediates and thereby play a role in the regulation of human progesterone synthesis and metabolism during pregnancy and near term.
8 citations
TL;DR: The present studies show that ReRF is not 17 beta-HSD or a modifier of that enzyme, and that in vitro Re-inactivating activity represents ReRF.
8 citations
TL;DR: Conversion of dehydroepiandrosterone to androstenedione by the partially purified Δ5-3β-hydroxysteroid dehydrogenase was inhibited exponentially by cyanoketone, and I50 was estimated 3.5 × 10−9 M.
8 citations
TL;DR: Preliminary studies were carried out to investigate the endogenous substrates and inhibitors of 11-hydroxysteroid dehydrogenase in human fetal tissues, using labelled cortisol and a homogenate of human placenta.
Abstract: A radioenzymaticassay (REA) is described, using labelled cortisol and a homogenate of human placenta. Steroids which are able to compete with the tracer for conversion to the 11-keto form can be measured. Of these, 11β and 11α-hydroxyprogesterone (11β-hydroxypregn-4-ene-3, 20-dione), 3β, 11β-dihydroxypregn-5-ene-20-one, 11β, 20α-dihydroxypregn-4-ene-3-one and corticosterone are the most active, while cortisol and prednisolone are moderately active. All other steroids tested competed less than 10% as effectively as 11β-hydroxyprogesterone at 50% conversion with no added substrate. The sensitivity was 0.8 ng of 11β-hydroxyprogesterone and 5 ng cortisol. Using this REA, preliminary studies were carried out to investigate the endogenous substrates and inhibitors of 11-hydroxysteroid dehydrogenase in human fetal tissues. Key Words: radioenzymaticassay, 11-hydroxysteroid dehydrogenase, human placenta, 11-hydroxysteroids.
01 Jan 1982
TL;DR: Five beta-Cholanoates, having a hydroxyl group in the 3 alpha and 3 beta and/or 12 alpha and 12 beta configurations, were tested as substrates for two preparation of 3 alpha-hydroxysteroid dehydrogenase (HSDH) and two preparations of 12 alpha-HSDH.
Abstract: 5 beta-Cholanoates, having a hydroxyl group in the 3 alpha and 3 beta and/or 12 alpha and 12 beta configurations, were tested as substrates for two preparation of 3 alpha-hydroxysteroid dehydrogenase (HSDH) and two preparations of 12 alpha-HSDH. When the 3-OH group was in the alpha configuration, both 3 alpha-HSDH preparations reacted, but when it was in the beta configuration, neither 3 alpha-HSDH preparations reacted. This also held true for the 12 alpha-HSDH preparations.
TL;DR: The solubilization of 17β-hydroxysteroid dehydrogenase from a rat liver microsomal preparation with the non-ionic detergent Triton X-100 resulted in a soluble fraction that contained 80% of the proteins and 75%" of the enzymatic activity of initial microsomes.