Showing papers on "Hydroxysteroid dehydrogenase published in 1979"
TL;DR: Increases in 17β-hydroxysteroid dehydrogenase activity, determined by measuring the rate of conversion of estradiol to estrone, were noted during incubations in the presence of progestins, which were about 20 times higher in secretory tissue than in proliferative endometrium.
Abstract: The activities of 17β and 20α-hydroxysteroid dehydrogenases in homogenates of human endometrium were measured using estradiol, testosterone, 5-androstene-3β,17β-diol, and 20α-dihydroprogesterone (20α-DHP) as substrates. All of these activities were about 20 times higher in secretory tissue than in proliferative endometrium. The rates of oxidation of the three 17β-hydroxysteroids tested were similar and about 4–8 times higher than the rate of oxidation of 20α-DHP under the same assay conditions. Fragments of proliferative endometrium were incubated under organ culture conditions for 1–3 days in either medium alone or medium to which various amounts of progesterone or medroxyprogesterone acetate were added. As reported before, 3 to 10-fold increases in 17β-hydroxysteroid dehydrogenase activity, determined by measuring the rate of conversion of estradiol to estrone, were noted during incubations in the presence of progestins. Similar increases were observed when testosterone, 5-androstene-3β,17β-diol, and 20...
65 citations
TL;DR: The effects of FSH, hCG, and PRL on the activity of 20 alpha-hydroxysteroid dehydrogenase of separate ovarian components of hypophysectomized, diethylstilbestrol-treated rats were studied and enzyme activity was found to reside mainly in granulosa cells.
Abstract: The effects of FSH, hCG, and PRL on the activity of 20α-hydroxysteroid dehydrogenase (20α-SDH) of separate ovarian components of hypophysectomized, diethylstilbestroltreated rats were studied. Enzyme activity was found to reside mainly in granulosa cells. FSH induced an increase in enzyme activity. A preparation of FSH was purified by adsorbing its LH contamination on rat corpora lutea membranes and by further neutralizing LH traces with an antiserum to the β-subunit of LH. This purified FSH retained the ability to induce a 6-fold increase in specific enzyme activity in granulosa cells of hypophysectomized, diethylstilbestrol-treated rats. Administration of hCG to rats treated with purified FSH, further enhanced 20α- SDH activity in granulosa cells up to 11.5-fold above control. PRL, which is known to inhibit 20α-SDH activity in regressing rat corpora lutea, suppressed the FSH-induced increase in enzyme activity in the granulosa cells.
41 citations
TL;DR: The results indicate that 17 beta-hydroxysteroid dehydrogenases may play important roles in the metabolism of exogeneous aldehydes and ketones as well as steroids.
Abstract: Two NADPH-dependent aromatic aldehyde-ketone reductases purified from guinea pig liver catalyzed oxidoreduction of 17 beta-hydroxysteroids and 17-ketosteroids. One enzyme efficiently oxidized 5 beta-androstanes and reduced 17-ketosteroids of A/B cis configuration, whereas the other enzyme efficiently oxidized 5 alpha-androstanes and equally reduced both 5 alpha-and 5 beta-androstanes of 17-ketosteroids. However, aromatic aldehydes and ketones, and 3-ketosteroids were irreversibly reduced by the two enzymes. The two enzymes utilized NADP+ or NADPH as cofactor, but little activity with NAD+ or NADH was found. Phosphate ions enhanced the NAD+-dependent dehydrogenase activity and NADH-dependent reductase activity of the two enzymes, whereas the activities with NADP+ and NADPH were not affected. The ratios of the two activities of ketone reduction and 17 beta-hydroxysteroid oxidation of the two enzymes were almost constant during the purification steps after the two enzymes had been separated by DEAE-cellulose chromatography. By kinetic studies and electrophoresis and isoelectric focusing experiments it was confirmed that both of the two enzymes were responsile for the reduction aldehydes, ketones, and ketosteroids and for the oxidation of 17 beta-hydroxysteroids. These results indicate that 17 beta-hydroxysteroid dehydrogenases may play important roles in the metabolism of exogeneous aldehydes and ketones as well as steroids.
31 citations
TL;DR: The results suggest that false negative receptor assays in the premenopausal women is not likely to be due to occupancy of receptors by endogenous estrogens, and the higher estrone content in the ER negative group is probably due to high 17 beta-hydroxysteroid dehydrogenase activity inherent to these tumor cells.
31 citations
TL;DR: A method for the quantitative measurement of Δ5, 3β-hydroxysteroid dehydrogenase activity in unfixed tissue sections of rat ovary based on the oxidation of dehydroepiandrosterone (DHEA) uses nitroblue tetrazolium as the final electron acceptor.
Abstract: A method for the quantitative measurement of Δ5, 3β-hydroxysteroid dehydrogenase activity in unfixed tissue sections of rat ovary has been described. The method depends on the oxidation of dehydroepiandrosterone (DHEA) and uses nitroblue tetrazolium as the final electron acceptor. Although the dehydrogenase is not a soluble enzyme, polyvinyl alcohol is included in the reaction medium to allow the use of a high substrate concentration whilst employing a low concentration (5%) of dimethyl formamide. The enzyme is equally dependent on NAD+ or NADP+ for its activity and this activity is significantly enhanced by the presence of cyanide. The NADP+ dependence is not abolished by inhibiting nonspecific alkaline phosphomonoesterase. The activity of Δ5, 3β-hydroxysteroid dehydrogenase is completely dependent on a functional sulphydryl group. Furthermore, the enzyme activity is totally inhibited in the presence of a steroid substrate analogue at 10−4 M.
25 citations
TL;DR: Subcellular distribution studies of 3β and 17β-hydroxysteroid dehydrogenase activity in Pseudomonas testosteroni revealed that much of the enzyme released from whole cells is in a soluble state, while the 1-ene-dehydrogenase appears to be more firmly membrane-bound.
25 citations
TL;DR: Subcellular fractionation of endometrial homogenate showed a maximal activity in the 105,000 x g ultracentrifugation microsomal pellet and a very low activity in cytosol, showing strong similarities between this enzyme and the one described in human endometrium.
16 citations
TL;DR: A modified method for the radiometric determination of hydroxysteroid dehydrogenase activities in rat liver, with improved precision and a radical reduction in the time involved in performing the assay is described.
Abstract: This paper described a modified method for the radiometric determination of hydroxysteroid dehydrogenase activities in rat liver. The principle advantages of this method are the improved precision and a radical reduction in the time involved in performing the assay. The procedure comprises the following steps: incubation of 14C-labelled substrate with coenzyme and cell fraction under optimized conditions; termination of the reaction by addition of organic solvent containing a defined amount of 3H-labelled reaction product; removal of precipitated protein and coenzyme by centrifugation; paper chromatographic isolation of the product; direct quantitation of 14C activity in the product zone of the paper chromatogram. The assay systems have been applied to elucidate and quantitate sex and strain differences in the activities of the above enzymes in Chbb/THOM and Sprague-Dawley rats.
13 citations
01 Apr 1979
TL;DR: The results indicate that, in rabbits exposed to NaF, a reduction in ascorbic acid content as well as a depletion of steroid dehydrogenase activity occurs especially at the zona glomerulosa.
Abstract: Rabbits were given 50 mg sodium fluoride/kg body weight through the intragastric route every 24 hours for a total period of 200 days. The left adrenal gland was removed and its total weight recorded. Adrenal glands from rabbits sacrificed at varying intervals for other investigative purposes were also collected and their weights recorded. The data indicate a significant rise in the total weight of the gland. Both ascorbic acid and steroid dehydrogenase (Delta 5-3Beta hydroxysteroid dehydrogenase) were localized in the adrenal gland by histochemical methods. The results indicate that, in rabbits exposed to NaF, a reduction in ascorbic acid content as well as a depletion of steroid dehydrogenase activity occurs especially at the zona glomerulosa. The significance of the increase in weight of the gland to the reduction of the ascorbic acid content and steroid dehydrogenase activity is discussed. 15 references, 4 figures.
12 citations
TL;DR: Uptake of testosterone by membrane vesicles and membrane bound 3β and 17β-hydroxysteroid dehydrogenase activity of Pseudomonas testosteroni were inhibited by diethylstilbestrol, estradiol-17α, hydroxymethylenesteroid and cyanoketosteroid.
11 citations
TL;DR: It was found that the 17β-hydroxysteroid dehydrogenase was mainly located in mitochondrial, microsomal and cytoplasmic fractions, and NADP was more efficient than NAD as cofactor.
TL;DR: The effects of actively immunizing rats with a purified preparation of Δ5-3B-OHSDH are reported and vaginal cytology and progesterone levels in plasma are examined.
Abstract: The effects of actively immunizing rats with a purified preparation of Δ5-3B-OHSDH are reported. The following parameters were examined: (1) vaginal cytology; (2) pregnancy; (3) antibody titres; (4) Δ5-3B-OHSDH activity in the ovary by (a) histochemical, (b) biochemical methods; (5) 20 α-OHSDH activity in the ovary determined histochemically; (6) progesterone levels in plasma.