An Enzyme in Endocrine Tissues which Oxidizes Δ
            <sup>5</sup>
            -3 Hydroxy Steroids to α,β Unsaturated Ketones

Samuels, Leo T.; Helmreich, M. L.; Lasater, M. B.; Reich, H.

doi:10.1126/science.113.2939.490

Cited by 205 publications

(41 citation statements)

References 6 publications

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“…For this purpose, we have used the enzyme A5-3/?-hydroxysteroid dehydrogenase (3/J-HSD) which has a well-defined position in steroid bio¬ synthesis (Samuels, Helmreich, Lasater & Reich, 1951), and can be demon¬ strated histochemically (Wattenberg, 1958). This enzyme catalyses the con¬ version of pregnenolone to progesterone, and of dehydroepiandrosterone (DHA) to androstenedione.…”

Section: Introductionmentioning

confidence: 99%

Distribution of 5-3 -Hydroxysteroid Dehydrogenase Activity in the Graafian Follicle of the Sheep

Hay¹,

Moor²

1975

Reproduction

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Summary. The localization of \g=D\5-3\g=b\-hydroxysteroiddehydrogenase (3\g=b\-HSD) has been examined in ovarian follicles in vivo and in vitro, and related to oestrogen and progesterone production.In When LH was added to the medium, oestrogen secretion was inhibited; within 48 hr, the follicles were secreting high levels of progesterone, and 3\g=b\-HSD activity was present in both the membrana granulosa and the theca interna. Dibutyryl cyclic adenosine monophosphate mimicked the effect of LH in suppressing oestrogen secretion, but did not induce production of progesterone; the distribution of 3\g=b\-HSDactivity in follicles treated with this nucleotide was the same as in those cultured in control medium.

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Section: Introductionmentioning

confidence: 99%

Distribution of 5-3 -Hydroxysteroid Dehydrogenase Activity in the Graafian Follicle of the Sheep

Hay¹,

Moor²

1975

Reproduction

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“…In bacteria, such as Pseudomonas species, the two consecutive steps are catalyzed by two distinct enzymes, a 3␤-hydroxysteroid dehydrogenase and a 3-ketosteroid isomerase (1). Mammalian tissues contain 3␤-hydroxysteroid dehydrogenases, which have been found to catalyze also the isomerase reaction (2)(3)(4). Extending the studies of the isomerization ( Fig.…”

mentioning

confidence: 99%

“…Pregnenolone is an obligatory intermediate in the biosynthesis of steroid hormones, and in the available alternative metabolic pathways its 3␤-hydroxyl group will eventually be oxidized to a ketone, and its ⌬ 5 double bond will be converted to the resonancestabilized ⌬ 4 isomer. For example, a reaction sequence leading to testosterone involves the 3␤-oxidation of dehydroepiandrosterone to ⌬ 5 -androstenedione followed by the isomerization of the product into ⌬ 4 -androstenedione (2). In mammalian tissues the oxidation is catalyzed by several pyridine-nucleotide-dependent 3␤-hydroxysteroid dehydrogenases.…”

mentioning

confidence: 99%

“…The multiple forms of GST are divided into different classes, based on their primary structures. The different classes of soluble mammalian GSTs have been denoted 2 Alpha, Mu, Pi (8), Theta (9), Sigma (10), Kappa (11), Zeta (12), and Omega (13). The proteins are dimers, each subunit containing a largely conserved GSH-binding site (G-site) and a more promiscuous site (H-site) for the second, electrophilic, substrate.…”

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confidence: 99%

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The Role of Glutathione in the Isomerization of Δ5-Androstene- 3,17-dione Catalyzed by Human Glutathione Transferase A1-1

Pettersson

Mannervik

2001

Journal of Biological Chemistry

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Human glutathione transferase (GST) A1-1 efficiently catalyzes the isomerization of ⌬ 5 -androstene-3,17-dione (AD) into ⌬ 4 -androstene-3,17-dione. High activity requires glutathione, but enzymatic catalysis occurs also in the absence of this cofactor. Glutathione alone shows a limited catalytic effect. S-Alkylglutathione derivatives do not promote the reaction, and the pH dependence of the isomerization indicates that the glutathione thiolate serves as a base in the catalytic mechanism. Mutation of the active-site Tyr 9 into Phe significantly decreases the steady-state kinetic parameters, alters their pH dependence, and increases the pK a value of the enzyme-bound glutathione thiol. Thus, Tyr 9 promotes the reaction via its phenolic hydroxyl group in protonated form. GST A2-2 has a catalytic efficiency with AD 100-fold lower than the homologous GST A1-1. Another Alpha class enzyme, GST A4-4, is 1000-fold less active than GST A1-1. The Y9F mutant of GST A1-1 is more efficient than GST A2-2 and GST A4-4, both having a glutathione cofactor and an active-site Tyr 9 residue. The active sites of GST A2-2 and GST A1-1 differ by only four amino acid residues, suggesting that proper orientation of AD in relation to the thiolate of glutathione is crucial for high catalytic efficiency in the isomerization reaction. The GST A1-1-catalyzed steroid isomerization provides a complement to the previously described isomerase activity of 3␤-hydroxysteroid dehydrogenase.

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“…Quantitative cytochemical analyses have de monstrated that the greatest amount of A5-3(3-hydroxysteroid dehydrogenase and glucose-6-phosphate dehy drogenase, two enzymes involved in steroid hormone biosynthesis [Samules et al, 1951;McKerns, 1969;Chayen et al. 1973].…”

Section: Introductionmentioning

confidence: 99%

A Quantitative Electron Microscopic Analysis of the Membrana granulosa of Rat Preovulatory Follicles

Zoller¹

1984

Cells Tissues Organs

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The ultrastructure of the membrana granulosa (MG) of rat preovulatory follicles was examined using stereological techniques. Organelles studied were nuclei, mitochondria, lipid droplets (LD), lysosomes, and smooth and rough endoplasmic reticulum (SER, RER). The peripheral region of the MG contained the greatest volume of mitochondria, LD and SER, organelles associated with steroidogenesis. The volume of RER, an organelle associated with protein production, was greatest in the cumulus oophorus. These results corroborate previous analyses and demonstrate that the rat MG is composed of discrete subregions.

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An Enzyme in Endocrine Tissues which Oxidizes Δ ⁵ -3 Hydroxy Steroids to α,β Unsaturated Ketones

Cited by 205 publications

References 6 publications

Distribution of 5-3 -Hydroxysteroid Dehydrogenase Activity in the Graafian Follicle of the Sheep

Distribution of 5-3 -Hydroxysteroid Dehydrogenase Activity in the Graafian Follicle of the Sheep

The Role of Glutathione in the Isomerization of Δ5-Androstene- 3,17-dione Catalyzed by Human Glutathione Transferase A1-1

A Quantitative Electron Microscopic Analysis of the Membrana granulosa of Rat Preovulatory Follicles

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An Enzyme in Endocrine Tissues which Oxidizes Δ 5 -3 Hydroxy Steroids to α,β Unsaturated Ketones

Cited by 205 publications

References 6 publications

Distribution of 5-3 -Hydroxysteroid Dehydrogenase Activity in the Graafian Follicle of the Sheep

Distribution of 5-3 -Hydroxysteroid Dehydrogenase Activity in the Graafian Follicle of the Sheep

The Role of Glutathione in the Isomerization of Δ5-Androstene- 3,17-dione Catalyzed by Human Glutathione Transferase A1-1

A Quantitative Electron Microscopic Analysis of the Membrana granulosa of Rat Preovulatory Follicles

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An Enzyme in Endocrine Tissues which Oxidizes Δ ⁵ -3 Hydroxy Steroids to α,β Unsaturated Ketones