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Conversion of 5 alpha-pregnane-3,20-dione, 3 alpha-hydroxy-5 alpha-pregnan-20-one and 3 beta-hydroxy-5 alpha-pregnan-20-one to delta 16-C19 steroids by the reconstituted delta 16-C19-steroid synthetase system. 1989

H Kohara, and K Shimizu, and N Yamaga
Division of Biochemistry, Tottori University School of Medicine, Yonago, Japan.

The substrate specificity of the reconstituted delta 16-C19-steroid synthetase system, which catalyzes the formation of 5,16-androstadien-3 beta-ol or 4,16-androstadien-3-one from pregnenolone or progesterone, respectively, was studied. The reconstituted system consisted of a partially purified cytochrome P-450, NADPH-cytochrome P-450 reductase, cytochrome b5 and NADH-cytochrome b5 reductase all from pig testicular microsomes. It was found that 5 alpha-reduced C21 steroids such as 5 alpha-pregnane-3,20-dione, 3 alpha-hydroxy-5 alpha-pregnan-20-one and 3 beta-hydroxy-5 alpha-pregnan-20-one can be substrates for the enzyme system, resulting in the formation of 5 alpha-androst-16-en-3-one, 5 alpha-androst-16-en-3 alpha-ol and 5 alpha-androst-16-en-3 beta-ol, respectively. The results suggest that 5 alpha-reduced delta 16-C19 steroids might be synthesized from pregnenolone and progesterone via 5 alpha-reduced C21 steroids as intermediates. The pathways would bypass 5,16-androstadien-3 beta-ol and 4,16-androstadien-3-one which have been assumed as obligatory intermediates in the formation of 5 alpha-reduced delta 16-C19 steroids from pregnenolone and progesterone.

UI MeSH Term Description Entries
D008297 Male Males
D008861 Microsomes Artifactual vesicles formed from the endoplasmic reticulum when cells are disrupted. They are isolated by differential centrifugation and are composed of three structural features: rough vesicles, smooth vesicles, and ribosomes. Numerous enzyme activities are associated with the microsomal fraction. (Glick, Glossary of Biochemistry and Molecular Biology, 1990; from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed) Microsome
D010088 Oxidoreductases The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9) Dehydrogenases,Oxidases,Oxidoreductase,Reductases,Dehydrogenase,Oxidase,Reductase
D011277 Pregnanediones Pregnane derivatives in which two side-chain methyl groups or two methylene groups in the ring skeleton (or a combination thereof) have been oxidized to keto groups. Diketopregnanes,Dioxopregnanes
D011278 Pregnanes Saturated derivatives of the steroid pregnane. The 5-beta series includes PROGESTERONE and related hormones; the 5-alpha series includes forms generally excreted in the urine.
D011280 Pregnanolone A pregnane found in the urine of pregnant women and sows. It has anesthetic, hypnotic, and sedative properties. Eltanolone,3 alpha, 5 beta-Tetrahydroprogesterone,3 alpha-Hydroxy-5 alpha-pregnan-20-one,3 alpha-Hydroxy-5 beta-pregnan-20-one,3-Hydroxypregnan-20-one,3beta-Hydroxy-5alpha-pregnan-20-one,Allopregnan-3 beta-ol-20-one,Allopregnanolone,Epipregnanolone,Pregnan-3alpha-ol-20-one,Pregnanolone, (3alpha)-isomer,Pregnanolone, (3alpha, 5beta, 17-alpha)-isomer,Pregnanolone, (3alpha,5alpha)-isomer,Pregnanolone, (3alpha,5beta)-isomer,Pregnanolone, (3beta)-isomer,Pregnanolone, (3beta, 5alpha)-isomer,Pregnanolone, (3beta, 5alpha, 17alpha)-isomer,Pregnanolone, (3beta, 5alpha, 8alpha, 17beta)-isomer,Pregnanolone, (3beta, 5beta)-isomer,Pregnanolone, (3beta, 5beta, 17alpha)-isomer,Pregnanolone, (3beta, 5beta,14beta)-isomer,Pregnanolone, (5alpha)-isomer,Sepranolone,3 Hydroxypregnan 20 one,3 alpha Hydroxy 5 alpha pregnan 20 one,3 alpha Hydroxy 5 beta pregnan 20 one,3 alpha, 5 beta Tetrahydroprogesterone,3beta Hydroxy 5alpha pregnan 20 one,Allopregnan 3 beta ol 20 one,Pregnan 3alpha ol 20 one,alpha-Hydroxy-5 alpha-pregnan-20-one, 3,alpha-Hydroxy-5 beta-pregnan-20-one, 3,alpha-pregnan-20-one, 3 alpha-Hydroxy-5,beta-ol-20-one, Allopregnan-3,beta-pregnan-20-one, 3 alpha-Hydroxy-5
D011284 Pregnenolone A 21-carbon steroid, derived from CHOLESTEROL and found in steroid hormone-producing tissues. Pregnenolone is the precursor to GONADAL STEROID HORMONES and the adrenal CORTICOSTEROIDS. 5-Pregnen-3-beta-ol-20-one,5 Pregnen 3 beta ol 20 one
D011374 Progesterone The major progestational steroid that is secreted primarily by the CORPUS LUTEUM and the PLACENTA. Progesterone acts on the UTERUS, the MAMMARY GLANDS and the BRAIN. It is required in EMBRYO IMPLANTATION; PREGNANCY maintenance, and the development of mammary tissue for MILK production. Progesterone, converted from PREGNENOLONE, also serves as an intermediate in the biosynthesis of GONADAL STEROID HORMONES and adrenal CORTICOSTEROIDS. Pregnenedione,Progesterone, (13 alpha,17 alpha)-(+-)-Isomer,Progesterone, (17 alpha)-Isomer,Progesterone, (9 beta,10 alpha)-Isomer
D000730 Androstadienes Derivatives of the steroid androstane having two double bonds at any site in any of the rings.
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia

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