Seasonal changes in the activity of cytochrome P450C17 from the testis of Bufo arenarum

In Bufo arenarum, the biosynthesis of testosterone and 5α-dihydrotestosterone takes place through a complete 5-ene pathway, 5-androsten-3β,17β-diol being the immediate precursor of testosterone. Besides androgens, testes are able to synthesise 5α-pregnan-3,20-dione and several 3α and 20α reduced der...

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Autores principales:	Solari, J.J.F., Pozzi, A.G., Ceballos, N.R.
Formato:	JOUR
Materias:	Cytochrome P450C17 Enzyme activity Kinetic parameters Seasonal changes Toad testis antiserum steroid 17alpha monooxygenase testosterone animal article blood cell fractionation kinetics male metabolism season testis tissue distribution toad Animals Bufo arenarum Immune Sera Kinetics Male Seasons Steroid 17-alpha-Hydroxylase Subcellular Fractions Testis Testosterone Tissue Distribution
Acceso en línea:	http://hdl.handle.net/20.500.12110/paper_01741578_v172_n8_p685_Solari
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	todo:paper_01741578_v172_n8_p685_Solari
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spelling	todo:paper_01741578_v172_n8_p685_Solari2023-10-03T15:07:48Z Seasonal changes in the activity of cytochrome P450C17 from the testis of Bufo arenarum Solari, J.J.F. Pozzi, A.G. Ceballos, N.R. Cytochrome P450C17 Enzyme activity Kinetic parameters Seasonal changes Toad testis antiserum steroid 17alpha monooxygenase testosterone animal article blood cell fractionation kinetics male metabolism season testis tissue distribution toad Animals Bufo arenarum Immune Sera Kinetics Male Seasons Steroid 17-alpha-Hydroxylase Subcellular Fractions Testis Testosterone Tissue Distribution In Bufo arenarum, the biosynthesis of testosterone and 5α-dihydrotestosterone takes place through a complete 5-ene pathway, 5-androsten-3β,17β-diol being the immediate precursor of testosterone. Besides androgens, testes are able to synthesise 5α-pregnan-3,20-dione and several 3α and 20α reduced derivatives. During the breeding season, steroid biosynthesis turns from androgen to C21-steroid production. As a consequence, the cytochrome P450 17-hydroxylase, C17,20-lyase (CypP450c17) could be a key enzyme in that metabolic shift. The present study demonstrates that in testes of B. arenarum, CypP450c17 co-localises with glucose-6-phosphatase in the microsomal fraction. CypP450c17 possesses more affinity for pregnenolone than for progesterone in both non-reproductive (Km=43.764±4.63 nM and 2,170±630 nM, respectively) and reproductive (Km=37.46± 4.19 nM and 3,060±190 nM, respectively) seasons. These results could explain the predominance of the 5-ene pathway for testosterone biosynthesis. Toad CypP450c17 activity is higher in the non-reproductive period than the reproductive period, suggesting that this enzyme is an important factor in toad steroidogenic changes. Animals in reproductive conditions showed a significant reduction in circulating androgens. This is in agreement with the decrease in Vmax of cytochrome P450 17-hydroxylase activity, enhancing the physiological relevance of these in vitro results. Fil:Pozzi, A.G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Ceballos, N.R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_01741578_v172_n8_p685_Solari
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Cytochrome P450C17 Enzyme activity Kinetic parameters Seasonal changes Toad testis antiserum steroid 17alpha monooxygenase testosterone animal article blood cell fractionation kinetics male metabolism season testis tissue distribution toad Animals Bufo arenarum Immune Sera Kinetics Male Seasons Steroid 17-alpha-Hydroxylase Subcellular Fractions Testis Testosterone Tissue Distribution
spellingShingle	Cytochrome P450C17 Enzyme activity Kinetic parameters Seasonal changes Toad testis antiserum steroid 17alpha monooxygenase testosterone animal article blood cell fractionation kinetics male metabolism season testis tissue distribution toad Animals Bufo arenarum Immune Sera Kinetics Male Seasons Steroid 17-alpha-Hydroxylase Subcellular Fractions Testis Testosterone Tissue Distribution Solari, J.J.F. Pozzi, A.G. Ceballos, N.R. Seasonal changes in the activity of cytochrome P450C17 from the testis of Bufo arenarum
topic_facet	Cytochrome P450C17 Enzyme activity Kinetic parameters Seasonal changes Toad testis antiserum steroid 17alpha monooxygenase testosterone animal article blood cell fractionation kinetics male metabolism season testis tissue distribution toad Animals Bufo arenarum Immune Sera Kinetics Male Seasons Steroid 17-alpha-Hydroxylase Subcellular Fractions Testis Testosterone Tissue Distribution
description	In Bufo arenarum, the biosynthesis of testosterone and 5α-dihydrotestosterone takes place through a complete 5-ene pathway, 5-androsten-3β,17β-diol being the immediate precursor of testosterone. Besides androgens, testes are able to synthesise 5α-pregnan-3,20-dione and several 3α and 20α reduced derivatives. During the breeding season, steroid biosynthesis turns from androgen to C21-steroid production. As a consequence, the cytochrome P450 17-hydroxylase, C17,20-lyase (CypP450c17) could be a key enzyme in that metabolic shift. The present study demonstrates that in testes of B. arenarum, CypP450c17 co-localises with glucose-6-phosphatase in the microsomal fraction. CypP450c17 possesses more affinity for pregnenolone than for progesterone in both non-reproductive (Km=43.764±4.63 nM and 2,170±630 nM, respectively) and reproductive (Km=37.46± 4.19 nM and 3,060±190 nM, respectively) seasons. These results could explain the predominance of the 5-ene pathway for testosterone biosynthesis. Toad CypP450c17 activity is higher in the non-reproductive period than the reproductive period, suggesting that this enzyme is an important factor in toad steroidogenic changes. Animals in reproductive conditions showed a significant reduction in circulating androgens. This is in agreement with the decrease in Vmax of cytochrome P450 17-hydroxylase activity, enhancing the physiological relevance of these in vitro results.
format	JOUR
author	Solari, J.J.F. Pozzi, A.G. Ceballos, N.R.
author_facet	Solari, J.J.F. Pozzi, A.G. Ceballos, N.R.
author_sort	Solari, J.J.F.
title	Seasonal changes in the activity of cytochrome P450C17 from the testis of Bufo arenarum
title_short	Seasonal changes in the activity of cytochrome P450C17 from the testis of Bufo arenarum
title_full	Seasonal changes in the activity of cytochrome P450C17 from the testis of Bufo arenarum
title_fullStr	Seasonal changes in the activity of cytochrome P450C17 from the testis of Bufo arenarum
title_full_unstemmed	Seasonal changes in the activity of cytochrome P450C17 from the testis of Bufo arenarum
title_sort	seasonal changes in the activity of cytochrome p450c17 from the testis of bufo arenarum
url	http://hdl.handle.net/20.500.12110/paper_01741578_v172_n8_p685_Solari
work_keys_str_mv	AT solarijjf seasonalchangesintheactivityofcytochromep450c17fromthetestisofbufoarenarum AT pozziag seasonalchangesintheactivityofcytochromep450c17fromthetestisofbufoarenarum AT ceballosnr seasonalchangesintheactivityofcytochromep450c17fromthetestisofbufoarenarum
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Seasonal changes in the activity of cytochrome P450C17 from the testis of Bufo arenarum

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