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: Pozzi, Andrea Gabriela, Ceballos, Nora Raquel
Publicado: 2002
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:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01741578_v172_n8_p685_Solari
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 paper:paper_01741578_v172_n8_p685_Solari
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spelling paper:paper_01741578_v172_n8_p685_Solari2023-06-08T15:18:54Z Seasonal changes in the activity of cytochrome P450C17 from the testis of Bufo arenarum Pozzi, Andrea Gabriela Ceballos, Nora Raquel 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. 2002 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01741578_v172_n8_p685_Solari 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
Pozzi, Andrea Gabriela
Ceballos, Nora Raquel
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.
author Pozzi, Andrea Gabriela
Ceballos, Nora Raquel
author_facet Pozzi, Andrea Gabriela
Ceballos, Nora Raquel
author_sort Pozzi, Andrea Gabriela
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
publishDate 2002
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_01741578_v172_n8_p685_Solari
http://hdl.handle.net/20.500.12110/paper_01741578_v172_n8_p685_Solari
work_keys_str_mv AT pozziandreagabriela seasonalchangesintheactivityofcytochromep450c17fromthetestisofbufoarenarum
AT ceballosnoraraquel seasonalchangesintheactivityofcytochromep450c17fromthetestisofbufoarenarum
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