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PubMed1994

Measurement of urinary androgen sulfates without previous hydrolysis: a tool to investigate adrenarche. Determination of total 17-ketosteroid sulfates.

According to published data the group of urinary total 17-ketosteroid sulfates appears to represent an index of overall adrenal androgen production, at least before the onset of puberty. To quantify total 17-ketosteroid sulfates a modified colorimetric assay based on the Zimmermann reaction was validated. 17-ketosteroid sulfates were measured without previous hydrolysis (as conjugated Zimmermann chromogens against authentic dehydroepiandrosterone sulfate (DHEAS) as assay standard) after C18 reversed-phase extraction and LH-20 chromatography. Intra- and inter-assay coefficients of variation were 8.4% (15.0%) and 5.9% (17.6%), respectively, at urinary 17-ketosteroid sulfate concentrations of 10.8 (1.9) nmol/ml. Recoveries observed in spiking and parallelism experiments varied between 88 and 102%. In a group of 4-year-old children showing a renal DHEAS output of less than 0.1 mumol/d/1.73 m2 (measured by radioimmunoassay) a relatively high median 17-ketosteroid sulfate excretion of 1.29 mumol/d/1.73 m2 was found. Older children aged 8 years as well as a group aged 12-14 years demonstrated only moderately higher urinary 17-ketosteroid sulfates whereas excretion of DHEAS/d/1.73 m2 more than tripled from age group to age group. For children from 8 years onwards, adolescents, and adults, linear regression analysis indicated that urinary DHEAS elevations seem to contribute with a constant proportion of approximately 70% to the increments of total urinary 17-ketosteroid sulfates. These findings suggest that the attainment of such a constant relationship (between the total 17-ketosteroid sulfates and their major component) from about 8 years of age onwards could represent the hormonal correlate of the completion of the continuous zona reticularis in the adrenal gland (developing around this age from a focal reticularis zone).

17-Ketosteroids↗
PubMed1990

Purification and characterization of 3-ketosteroid-delta 1-dehydrogenase from Nocardia corallina.

The inducible 3-ketosteroid-delta 1-dehydrogenase of Nocardia corallina which catalyzes the introduction of a double bond into the position of carbon 1 and 2 of ring A of 3-ketosteroid has been obtained in four steps with a 50% yield and 360-fold purification. The enzyme is homogeneous as judged by SDS-gel electrophoresis and is a monomeric protein with a molecular weight of 60,500. The isoelectric point of the enzyme is about 3.1. The enzyme contains 1 mol of flavin adenine dinucleotide per mol of protein, and has a typical flavoprotein absorption spectrum with maxima of 458, 362 and 268 nm. The enzyme is very stable in the absence of added cofactors, and catalyzes the dehydrogenation of delta 4-3-ketosteroids in the presence of phenazine methosulfate, which acts as an excellent electron acceptor. Potassium ferricyanide and cytochrome c did not act as electron acceptors. The delta 1-dehydrogenation was also stimulated by molecular oxygen with stoichiometric production of hydrogen peroxide and delta 1,4-3-ketosteroid. The optimum pH is 10 for dehydrogenation using phenazine methosulfate, and is between 8.5 and 10 for the oxidase reaction. The enzyme oxidizes a wide variety of 3-ketosteroids, but not 3 beta-hydroxysteroids. 3-Ketosteroids having an 11 alpha- or 11 beta-hydroxyl group were oxidized at slow rates. The purified enzyme catalyzes efficiently aromatization of the A-ring of 19-nortestosterone and 19-norandrostenedione to produce estradiol and estrone. 19-Hydroxytestosterone, 19-hydroxyandrostenedion and 19-oxotestosterone were converted to the respective phenolic steroids with cleavage of the C10 side-chain. Activities of 3-ketosteroid-delta 4-dehydrogenase, delta 5-3-ketosteroid-4,5-isomerase, 3 beta-hydroxysteroid dehydrogenase and 17 beta-hydroxysteroid dehydrogenase were not observed in the purified preparations. Properties of this novel flavoprotein enzyme are discussed.

Amino Acids↗
PubMed1992

Human ovarian 17-ketosteroid oxidoreductase: unique characteristics of the granulosa-luteal cell and stromal enzyme.

OBJECTIVES: We attempted to test the hypothesis that distinct forms of the 17-ketosteroid oxidoreductase exist in the human ovary and to compare its activity in stroma obtained from normally cycling women and from hyperandrogenic women. STUDY DESIGN: Human ovarian granulosa-luteal cell and stromal 17-ketosteroid oxidoreductase were examined in cell incubations and subcellular homogenates. RESULTS: In subcellular homogenates of granulosa-luteal cells 17-ketosteroid oxidoreductase activity was greater in the cytosol fraction than in the membrane fraction. In contrast, in homogenates of both ovarian stroma and Leydig cells its activity was greater in the membrane fraction than in the cytosol fraction. At the substrate concentrations used estrone was a better substrate than androstenedione for the granulosa-luteal cell 17-ketosteroid oxidoreductase. In contrast, androstenedione was a better substrate than estrone for that in ovarian stromal and Leydig cell membranes. In incubations of ovarian stroma from hyperandrogenic women, significantly more testosterone accumulated in the medium per milligram of tissue than in the medium of incubations of ovarian stroma from normally cycling women (142 +/- 48 vs 7.9 +/- 7.5 pg testosterone per milligram of tissue per 48 hours, mean +/- SD, p less than 0.05). The ratio of testosterone to androstenedione was significantly higher in the medium of incubations of ovarian stroma from hyperandrogenic women than in that from normally cycling women (0.61 vs 0.25, mean, p less than 0.05). The ratio of serum testosterone to androstenedione was significantly greater in hyperandrogenic women than in normally cycling control women (0.31 +/- 0.11 vs 0.20 +/- 0.03, mean +/- SD, p less than 0.05). CONCLUSION: The localization (cytosol fraction) and substrate specificity (estrone) of the granulosa-luteal cell 17-ketosteroid oxidoreductase enzyme resembles that seen in human placenta. The localization (membrane fraction) and substrate specificity (androstenedione) of the ovarian stromal 17-ketosteroid oxidoreductase enzyme resembles that seen in Leydig cells. It may be one enzyme that exists in multiple forms or it may be two (or more) enzymes. In some hyperandrogenic women the ovarian stromal 17-ketosteroid oxidoreductase may be more active than in normally cycling women, contributing to an abnormally increased testosterone production rate.

17-Hydroxysteroid Dehydrogenases↗
PubMed1979

Effect of dexamethasone and ACTH on the secretion pattern of fractionated 17-ketosteroids in hirsutism.

Urinary steroid fractionations of 17-ketosteroids were carried out in 3 normally-ovulating young women and in 2 women with hirsutism. Dehydroepiandrosterone, aetiocholanolone, androsterone, 11 beta-hydroxyaetiocholanolone, 11 beta-hydroxyandrosterone, 11-oxoaetiocholanolone and 11-oxondrosterone were determined quantitatively by paper chromatography. Both patients had decreased levels of 11-deoxy and 11-oxy-17-ketosteroids compared with the normals. The ready suppression of 11-oxy-17-ketosteroids and the poor suppression of 11-deoxy-17-ketosteroids by dexamethasone in both patients suggests an ovarian origin of 11-deoxy-17-ketosteroids. Supporting evidence for an ovarian origin in Case 1 was furnished by the poor suppression of testosterone by dexamethasone and lack of response to ACTH stimulation of the adrenal glands. The presented data emphasize that the precursor of 11-deoxy-17-ketosteroids of ovarian origin, possibly testosterone, may well be the cause of hirsutism in both patients.

17-Ketosteroids↗
PubMed1974

[Behavior of neutral 17-ketosteroids in the urine of female pigs].

Ketosteroids were determined colorimetrically in samples of 24-hour urine from sows, ten days after service. Pregnancy was diagnosed by injection of the "Gravignost-swine" preparation in eight sows. Significant differences between the 17-ketosteroid excretion on non-pregnant sows were revealed by the excretion in 24-hour urine, but not by urinary concentration expressed in mg per litre. Injection of "Gravignost" had no effect on 17-ketosteroid values. In pregnant sows the urinary concentration of 17-ketosteroids was inversely proportional to daily urine volume, and there was also a significant correlation between urine volume and 17-ketosteroid excretion expressed in mg per 24 hours. The method used for determining urinary ketosteroids was sufficiently reliable and simple to be used for routine testing.

Animals↗
PubMed2000

Determination of delta4-3-ketosteroids based on oxime formation by difference circular dichroism spectroscopy.

delta4-3-Ketosteroids exhibit an intensive negative Cotton effect on the circular dichroism (CD) spectra in the wavelength range for the n-pi* electronic transition (270-350 nm). With hydroxylamine hydrochloride, delta4-3-ketosteroid compounds can be transformed into oxime derivatives. Following oxime formation, positive ellipticity with low intensity can be registered in this wavelength range. The quantitative determination of delta4-3-ketosteroids is based on the considerable difference between the ellipticities before and after oxime formation. The difference ellipticity for the six ketosteroids examined (norethisterone, levonorgestrel, levonorgestrel acetate, methyltestosterone, testosterone phenylpropionate, nortestosterone phenylpropionate) varies linearly with the concentration in the interval 6 x 10(-6)-3 x 10(-3) mol/L. The method can be well applied to determination of delta4-3-ketosteroid contamination of norgestimate [(+)-13-ethyl-17-hydroxy-18,19-dinor-17alpha-pregn4-en-20-yn-3-one oxime acetate]; 0.02-10% impurity can be measured.

Circular Dichroism↗