Mitochondrial localization of 3β-hydroxysteroid dehydrogenase 5-ene isomerase in interrenals of the toad Bufo arenarum H.
The enzymatic activity of 3β-hydroxysteroid dehydrogenase 5-ene isomerase (3βHSD/I) catalyzes an essential step in the biosynthesis of steroid hormones including progesterone, mineralocorticoids, glucocorticoids, estrogens, and androgens. Its subcellular localization in steroidogenic tissues is usua...
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1996
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00166480_v103_n2_p176_Pozzi http://hdl.handle.net/20.500.12110/paper_00166480_v103_n2_p176_Pozzi |
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paper:paper_00166480_v103_n2_p176_Pozzi2023-06-08T14:38:16Z Mitochondrial localization of 3β-hydroxysteroid dehydrogenase 5-ene isomerase in interrenals of the toad Bufo arenarum H. 3(or 17)beta hydroxysteroid dehydrogenase animal tissue article cellular distribution enzyme activity enzyme localization male nonhuman priority journal steroidogenesis tissue distribution toad The enzymatic activity of 3β-hydroxysteroid dehydrogenase 5-ene isomerase (3βHSD/I) catalyzes an essential step in the biosynthesis of steroid hormones including progesterone, mineralocorticoids, glucocorticoids, estrogens, and androgens. Its subcellular localization in steroidogenic tissues is usually considered to be mainly microsomal. The present study demonstrates that in the interrenal of Bufo arenarum H., 3βHSD/I activity localizes in mitochondria and micromes. It also shows that the two distinct pathways to aldosterone previously demonstrated for interrenals of B. arenarum H. exhibit differential subcellular localizations, microsomal for the 4-ene route and mitochondrial for the 5- ene route. Kinetic constants of 3βHSD/I were determined for the oxidation of pregnenolone and the recently described 3β-hydroxy analogue of aldosterone (3βAA). The preferred substrate of the mitochondrial 3βHSD/I enzyme was 3βAA (K(m) = 0.7 μM and 14.0 μM for 3βAA and pregnenolone, respectively). However, the microsomal enzyme has a greater affinity for pregnenolone (K(m) = 0.8 μM) than for 3βAA (K(m) = 17.0). Enzymes from both localizations have similar nucleotide (NAD+) requirements, activities being higher in summer. This dual localization opens novel possibilities for the regulation of interrenal functions. 1996 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00166480_v103_n2_p176_Pozzi http://hdl.handle.net/20.500.12110/paper_00166480_v103_n2_p176_Pozzi |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
3(or 17)beta hydroxysteroid dehydrogenase animal tissue article cellular distribution enzyme activity enzyme localization male nonhuman priority journal steroidogenesis tissue distribution toad |
| spellingShingle |
3(or 17)beta hydroxysteroid dehydrogenase animal tissue article cellular distribution enzyme activity enzyme localization male nonhuman priority journal steroidogenesis tissue distribution toad Mitochondrial localization of 3β-hydroxysteroid dehydrogenase 5-ene isomerase in interrenals of the toad Bufo arenarum H. |
| topic_facet |
3(or 17)beta hydroxysteroid dehydrogenase animal tissue article cellular distribution enzyme activity enzyme localization male nonhuman priority journal steroidogenesis tissue distribution toad |
| description |
The enzymatic activity of 3β-hydroxysteroid dehydrogenase 5-ene isomerase (3βHSD/I) catalyzes an essential step in the biosynthesis of steroid hormones including progesterone, mineralocorticoids, glucocorticoids, estrogens, and androgens. Its subcellular localization in steroidogenic tissues is usually considered to be mainly microsomal. The present study demonstrates that in the interrenal of Bufo arenarum H., 3βHSD/I activity localizes in mitochondria and micromes. It also shows that the two distinct pathways to aldosterone previously demonstrated for interrenals of B. arenarum H. exhibit differential subcellular localizations, microsomal for the 4-ene route and mitochondrial for the 5- ene route. Kinetic constants of 3βHSD/I were determined for the oxidation of pregnenolone and the recently described 3β-hydroxy analogue of aldosterone (3βAA). The preferred substrate of the mitochondrial 3βHSD/I enzyme was 3βAA (K(m) = 0.7 μM and 14.0 μM for 3βAA and pregnenolone, respectively). However, the microsomal enzyme has a greater affinity for pregnenolone (K(m) = 0.8 μM) than for 3βAA (K(m) = 17.0). Enzymes from both localizations have similar nucleotide (NAD+) requirements, activities being higher in summer. This dual localization opens novel possibilities for the regulation of interrenal functions. |
| title |
Mitochondrial localization of 3β-hydroxysteroid dehydrogenase 5-ene isomerase in interrenals of the toad Bufo arenarum H. |
| title_short |
Mitochondrial localization of 3β-hydroxysteroid dehydrogenase 5-ene isomerase in interrenals of the toad Bufo arenarum H. |
| title_full |
Mitochondrial localization of 3β-hydroxysteroid dehydrogenase 5-ene isomerase in interrenals of the toad Bufo arenarum H. |
| title_fullStr |
Mitochondrial localization of 3β-hydroxysteroid dehydrogenase 5-ene isomerase in interrenals of the toad Bufo arenarum H. |
| title_full_unstemmed |
Mitochondrial localization of 3β-hydroxysteroid dehydrogenase 5-ene isomerase in interrenals of the toad Bufo arenarum H. |
| title_sort |
mitochondrial localization of 3β-hydroxysteroid dehydrogenase 5-ene isomerase in interrenals of the toad bufo arenarum h. |
| publishDate |
1996 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00166480_v103_n2_p176_Pozzi http://hdl.handle.net/20.500.12110/paper_00166480_v103_n2_p176_Pozzi |
| _version_ |
1768541781151973376 |