Inhibition of rat liver microsomal estrogen 2-hydroxylase by 2-methoxyestrogens
The inhibition of estrogen 2-hydroxylase by 2-methoxyestrogens was demonstrated in screening assays and has been further investigated under initial velocity conditions. The ability of 2-methoxyestradiol and 2-methoxyestrone to block the conversion of estradiol to 2-hydroxyestradiol by male rat liver...
Ausführliche Beschreibung
Gespeichert in:
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| Format: |
E-Artikel |
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| Sprache: |
Englisch |
| Erschienen: |
1989 |
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| Reproduktion: |
Elsevier Journal Backfiles on ScienceDirect 1907 - 2002 |
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| Übergeordnetes Werk: |
in: Journal of Steroid Biochemistry - Amsterdam : Elsevier, 33(1989), 4, Seite 589-593 |
| Übergeordnetes Werk: |
volume:33 ; year:1989 ; number:4 ; pages:589-593 |
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| 520 | |a The inhibition of estrogen 2-hydroxylase by 2-methoxyestrogens was demonstrated in screening assays and has been further investigated under initial velocity conditions. The ability of 2-methoxyestradiol and 2-methoxyestrone to block the conversion of estradiol to 2-hydroxyestradiol by male rat liver microsomal preparations was determined by measuring the release of ^3H"2O from [2-^3H]estradiol. The apparent K"is were found to be 34.86 μM for 2-methoxyestradiol and 18.65μM for the methoxyestrone, with the apparent K"m for the substrate estradiol in these essays of 3.21 μM. Mixed inhibition studies with the methoxyestrogens and 2,4-dibromoestradiol, an effective estrogen 2-hydroxylase inhibitor, in male rat liver microsomes resulted in Dixon plots consisting of a series of parallel lines. Thus, methoxyestrogens and 2,4-dibromoestradiol are mutually exlusive inhibitors, i.e., the binding of one compound to the enzyme interferes with the binding of the other. These results indicate that the compounds are interacting at the same enzymatic site. Finally, a method utilized to measure estrogen 2-hydroxylase activity in vitro is a radioenzymatic assay involving addition of catechol o-methyltransferase (COMT) and radiolabeled S-adenosylmethionine, and the amount of catechol estrogens formed is determined by the amount of radiolabeled methoxyestrogens isolated. The results described here demonstrate inhibition of estrogen 2-hydroxylase by methoxyestrogens; however, under enzymatic conditions of low product formation, the estrogen 2-hydroxylase inhibitory effect of catechol estrogen products from the radioenzymatic assay would be insignificant. Thus, these interactions of methoxyestrogens suggest that the steroid hormonal environment be considered in the examination of estrogen 2-hydroxylase and the catechol estrogen products. | ||
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(DE-627)NLEJ18632538X (DE-599)GBVNLZ18632538X DE-627 ger DE-627 rakwb eng Inhibition of rat liver microsomal estrogen 2-hydroxylase by 2-methoxyestrogens 1989 nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier The inhibition of estrogen 2-hydroxylase by 2-methoxyestrogens was demonstrated in screening assays and has been further investigated under initial velocity conditions. The ability of 2-methoxyestradiol and 2-methoxyestrone to block the conversion of estradiol to 2-hydroxyestradiol by male rat liver microsomal preparations was determined by measuring the release of ^3H"2O from [2-^3H]estradiol. The apparent K"is were found to be 34.86 μM for 2-methoxyestradiol and 18.65μM for the methoxyestrone, with the apparent K"m for the substrate estradiol in these essays of 3.21 μM. Mixed inhibition studies with the methoxyestrogens and 2,4-dibromoestradiol, an effective estrogen 2-hydroxylase inhibitor, in male rat liver microsomes resulted in Dixon plots consisting of a series of parallel lines. Thus, methoxyestrogens and 2,4-dibromoestradiol are mutually exlusive inhibitors, i.e., the binding of one compound to the enzyme interferes with the binding of the other. These results indicate that the compounds are interacting at the same enzymatic site. Finally, a method utilized to measure estrogen 2-hydroxylase activity in vitro is a radioenzymatic assay involving addition of catechol o-methyltransferase (COMT) and radiolabeled S-adenosylmethionine, and the amount of catechol estrogens formed is determined by the amount of radiolabeled methoxyestrogens isolated. The results described here demonstrate inhibition of estrogen 2-hydroxylase by methoxyestrogens; however, under enzymatic conditions of low product formation, the estrogen 2-hydroxylase inhibitory effect of catechol estrogen products from the radioenzymatic assay would be insignificant. Thus, these interactions of methoxyestrogens suggest that the steroid hormonal environment be considered in the examination of estrogen 2-hydroxylase and the catechol estrogen products. Elsevier Journal Backfiles on ScienceDirect 1907 - 2002 Brueggemeier, R.W. oth Singh, U. oth in Journal of Steroid Biochemistry Amsterdam : Elsevier 33(1989), 4, Seite 589-593 (DE-627)NLEJ18527725X (DE-600)2198730-0 0022-4731 nnns volume:33 year:1989 number:4 pages:589-593 http://linkinghub.elsevier.com/retrieve/pii/0022-4731(89)90045-9 GBV_USEFLAG_H ZDB-1-SDJ GBV_NL_ARTICLE AR 33 1989 4 589-593 |
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(DE-627)NLEJ18632538X (DE-599)GBVNLZ18632538X DE-627 ger DE-627 rakwb eng Inhibition of rat liver microsomal estrogen 2-hydroxylase by 2-methoxyestrogens 1989 nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier The inhibition of estrogen 2-hydroxylase by 2-methoxyestrogens was demonstrated in screening assays and has been further investigated under initial velocity conditions. The ability of 2-methoxyestradiol and 2-methoxyestrone to block the conversion of estradiol to 2-hydroxyestradiol by male rat liver microsomal preparations was determined by measuring the release of ^3H"2O from [2-^3H]estradiol. The apparent K"is were found to be 34.86 μM for 2-methoxyestradiol and 18.65μM for the methoxyestrone, with the apparent K"m for the substrate estradiol in these essays of 3.21 μM. Mixed inhibition studies with the methoxyestrogens and 2,4-dibromoestradiol, an effective estrogen 2-hydroxylase inhibitor, in male rat liver microsomes resulted in Dixon plots consisting of a series of parallel lines. Thus, methoxyestrogens and 2,4-dibromoestradiol are mutually exlusive inhibitors, i.e., the binding of one compound to the enzyme interferes with the binding of the other. These results indicate that the compounds are interacting at the same enzymatic site. Finally, a method utilized to measure estrogen 2-hydroxylase activity in vitro is a radioenzymatic assay involving addition of catechol o-methyltransferase (COMT) and radiolabeled S-adenosylmethionine, and the amount of catechol estrogens formed is determined by the amount of radiolabeled methoxyestrogens isolated. The results described here demonstrate inhibition of estrogen 2-hydroxylase by methoxyestrogens; however, under enzymatic conditions of low product formation, the estrogen 2-hydroxylase inhibitory effect of catechol estrogen products from the radioenzymatic assay would be insignificant. Thus, these interactions of methoxyestrogens suggest that the steroid hormonal environment be considered in the examination of estrogen 2-hydroxylase and the catechol estrogen products. Elsevier Journal Backfiles on ScienceDirect 1907 - 2002 Brueggemeier, R.W. oth Singh, U. oth in Journal of Steroid Biochemistry Amsterdam : Elsevier 33(1989), 4, Seite 589-593 (DE-627)NLEJ18527725X (DE-600)2198730-0 0022-4731 nnns volume:33 year:1989 number:4 pages:589-593 http://linkinghub.elsevier.com/retrieve/pii/0022-4731(89)90045-9 GBV_USEFLAG_H ZDB-1-SDJ GBV_NL_ARTICLE AR 33 1989 4 589-593 |
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(DE-627)NLEJ18632538X (DE-599)GBVNLZ18632538X DE-627 ger DE-627 rakwb eng Inhibition of rat liver microsomal estrogen 2-hydroxylase by 2-methoxyestrogens 1989 nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier The inhibition of estrogen 2-hydroxylase by 2-methoxyestrogens was demonstrated in screening assays and has been further investigated under initial velocity conditions. The ability of 2-methoxyestradiol and 2-methoxyestrone to block the conversion of estradiol to 2-hydroxyestradiol by male rat liver microsomal preparations was determined by measuring the release of ^3H"2O from [2-^3H]estradiol. The apparent K"is were found to be 34.86 μM for 2-methoxyestradiol and 18.65μM for the methoxyestrone, with the apparent K"m for the substrate estradiol in these essays of 3.21 μM. Mixed inhibition studies with the methoxyestrogens and 2,4-dibromoestradiol, an effective estrogen 2-hydroxylase inhibitor, in male rat liver microsomes resulted in Dixon plots consisting of a series of parallel lines. Thus, methoxyestrogens and 2,4-dibromoestradiol are mutually exlusive inhibitors, i.e., the binding of one compound to the enzyme interferes with the binding of the other. These results indicate that the compounds are interacting at the same enzymatic site. Finally, a method utilized to measure estrogen 2-hydroxylase activity in vitro is a radioenzymatic assay involving addition of catechol o-methyltransferase (COMT) and radiolabeled S-adenosylmethionine, and the amount of catechol estrogens formed is determined by the amount of radiolabeled methoxyestrogens isolated. The results described here demonstrate inhibition of estrogen 2-hydroxylase by methoxyestrogens; however, under enzymatic conditions of low product formation, the estrogen 2-hydroxylase inhibitory effect of catechol estrogen products from the radioenzymatic assay would be insignificant. Thus, these interactions of methoxyestrogens suggest that the steroid hormonal environment be considered in the examination of estrogen 2-hydroxylase and the catechol estrogen products. Elsevier Journal Backfiles on ScienceDirect 1907 - 2002 Brueggemeier, R.W. oth Singh, U. oth in Journal of Steroid Biochemistry Amsterdam : Elsevier 33(1989), 4, Seite 589-593 (DE-627)NLEJ18527725X (DE-600)2198730-0 0022-4731 nnns volume:33 year:1989 number:4 pages:589-593 http://linkinghub.elsevier.com/retrieve/pii/0022-4731(89)90045-9 GBV_USEFLAG_H ZDB-1-SDJ GBV_NL_ARTICLE AR 33 1989 4 589-593 |
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(DE-627)NLEJ18632538X (DE-599)GBVNLZ18632538X DE-627 ger DE-627 rakwb eng Inhibition of rat liver microsomal estrogen 2-hydroxylase by 2-methoxyestrogens 1989 nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier The inhibition of estrogen 2-hydroxylase by 2-methoxyestrogens was demonstrated in screening assays and has been further investigated under initial velocity conditions. The ability of 2-methoxyestradiol and 2-methoxyestrone to block the conversion of estradiol to 2-hydroxyestradiol by male rat liver microsomal preparations was determined by measuring the release of ^3H"2O from [2-^3H]estradiol. The apparent K"is were found to be 34.86 μM for 2-methoxyestradiol and 18.65μM for the methoxyestrone, with the apparent K"m for the substrate estradiol in these essays of 3.21 μM. Mixed inhibition studies with the methoxyestrogens and 2,4-dibromoestradiol, an effective estrogen 2-hydroxylase inhibitor, in male rat liver microsomes resulted in Dixon plots consisting of a series of parallel lines. Thus, methoxyestrogens and 2,4-dibromoestradiol are mutually exlusive inhibitors, i.e., the binding of one compound to the enzyme interferes with the binding of the other. These results indicate that the compounds are interacting at the same enzymatic site. Finally, a method utilized to measure estrogen 2-hydroxylase activity in vitro is a radioenzymatic assay involving addition of catechol o-methyltransferase (COMT) and radiolabeled S-adenosylmethionine, and the amount of catechol estrogens formed is determined by the amount of radiolabeled methoxyestrogens isolated. The results described here demonstrate inhibition of estrogen 2-hydroxylase by methoxyestrogens; however, under enzymatic conditions of low product formation, the estrogen 2-hydroxylase inhibitory effect of catechol estrogen products from the radioenzymatic assay would be insignificant. Thus, these interactions of methoxyestrogens suggest that the steroid hormonal environment be considered in the examination of estrogen 2-hydroxylase and the catechol estrogen products. Elsevier Journal Backfiles on ScienceDirect 1907 - 2002 Brueggemeier, R.W. oth Singh, U. oth in Journal of Steroid Biochemistry Amsterdam : Elsevier 33(1989), 4, Seite 589-593 (DE-627)NLEJ18527725X (DE-600)2198730-0 0022-4731 nnns volume:33 year:1989 number:4 pages:589-593 http://linkinghub.elsevier.com/retrieve/pii/0022-4731(89)90045-9 GBV_USEFLAG_H ZDB-1-SDJ GBV_NL_ARTICLE AR 33 1989 4 589-593 |
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(DE-627)NLEJ18632538X (DE-599)GBVNLZ18632538X DE-627 ger DE-627 rakwb eng Inhibition of rat liver microsomal estrogen 2-hydroxylase by 2-methoxyestrogens 1989 nicht spezifiziert zzz rdacontent nicht spezifiziert z rdamedia nicht spezifiziert zu rdacarrier The inhibition of estrogen 2-hydroxylase by 2-methoxyestrogens was demonstrated in screening assays and has been further investigated under initial velocity conditions. The ability of 2-methoxyestradiol and 2-methoxyestrone to block the conversion of estradiol to 2-hydroxyestradiol by male rat liver microsomal preparations was determined by measuring the release of ^3H"2O from [2-^3H]estradiol. The apparent K"is were found to be 34.86 μM for 2-methoxyestradiol and 18.65μM for the methoxyestrone, with the apparent K"m for the substrate estradiol in these essays of 3.21 μM. Mixed inhibition studies with the methoxyestrogens and 2,4-dibromoestradiol, an effective estrogen 2-hydroxylase inhibitor, in male rat liver microsomes resulted in Dixon plots consisting of a series of parallel lines. Thus, methoxyestrogens and 2,4-dibromoestradiol are mutually exlusive inhibitors, i.e., the binding of one compound to the enzyme interferes with the binding of the other. These results indicate that the compounds are interacting at the same enzymatic site. Finally, a method utilized to measure estrogen 2-hydroxylase activity in vitro is a radioenzymatic assay involving addition of catechol o-methyltransferase (COMT) and radiolabeled S-adenosylmethionine, and the amount of catechol estrogens formed is determined by the amount of radiolabeled methoxyestrogens isolated. The results described here demonstrate inhibition of estrogen 2-hydroxylase by methoxyestrogens; however, under enzymatic conditions of low product formation, the estrogen 2-hydroxylase inhibitory effect of catechol estrogen products from the radioenzymatic assay would be insignificant. Thus, these interactions of methoxyestrogens suggest that the steroid hormonal environment be considered in the examination of estrogen 2-hydroxylase and the catechol estrogen products. Elsevier Journal Backfiles on ScienceDirect 1907 - 2002 Brueggemeier, R.W. oth Singh, U. oth in Journal of Steroid Biochemistry Amsterdam : Elsevier 33(1989), 4, Seite 589-593 (DE-627)NLEJ18527725X (DE-600)2198730-0 0022-4731 nnns volume:33 year:1989 number:4 pages:589-593 http://linkinghub.elsevier.com/retrieve/pii/0022-4731(89)90045-9 GBV_USEFLAG_H ZDB-1-SDJ GBV_NL_ARTICLE AR 33 1989 4 589-593 |
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inhibition of rat liver microsomal estrogen 2-hydroxylase by 2-methoxyestrogens |
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Inhibition of rat liver microsomal estrogen 2-hydroxylase by 2-methoxyestrogens |
| abstract |
The inhibition of estrogen 2-hydroxylase by 2-methoxyestrogens was demonstrated in screening assays and has been further investigated under initial velocity conditions. The ability of 2-methoxyestradiol and 2-methoxyestrone to block the conversion of estradiol to 2-hydroxyestradiol by male rat liver microsomal preparations was determined by measuring the release of ^3H"2O from [2-^3H]estradiol. The apparent K"is were found to be 34.86 μM for 2-methoxyestradiol and 18.65μM for the methoxyestrone, with the apparent K"m for the substrate estradiol in these essays of 3.21 μM. Mixed inhibition studies with the methoxyestrogens and 2,4-dibromoestradiol, an effective estrogen 2-hydroxylase inhibitor, in male rat liver microsomes resulted in Dixon plots consisting of a series of parallel lines. Thus, methoxyestrogens and 2,4-dibromoestradiol are mutually exlusive inhibitors, i.e., the binding of one compound to the enzyme interferes with the binding of the other. These results indicate that the compounds are interacting at the same enzymatic site. Finally, a method utilized to measure estrogen 2-hydroxylase activity in vitro is a radioenzymatic assay involving addition of catechol o-methyltransferase (COMT) and radiolabeled S-adenosylmethionine, and the amount of catechol estrogens formed is determined by the amount of radiolabeled methoxyestrogens isolated. The results described here demonstrate inhibition of estrogen 2-hydroxylase by methoxyestrogens; however, under enzymatic conditions of low product formation, the estrogen 2-hydroxylase inhibitory effect of catechol estrogen products from the radioenzymatic assay would be insignificant. Thus, these interactions of methoxyestrogens suggest that the steroid hormonal environment be considered in the examination of estrogen 2-hydroxylase and the catechol estrogen products. |
| abstractGer |
The inhibition of estrogen 2-hydroxylase by 2-methoxyestrogens was demonstrated in screening assays and has been further investigated under initial velocity conditions. The ability of 2-methoxyestradiol and 2-methoxyestrone to block the conversion of estradiol to 2-hydroxyestradiol by male rat liver microsomal preparations was determined by measuring the release of ^3H"2O from [2-^3H]estradiol. The apparent K"is were found to be 34.86 μM for 2-methoxyestradiol and 18.65μM for the methoxyestrone, with the apparent K"m for the substrate estradiol in these essays of 3.21 μM. Mixed inhibition studies with the methoxyestrogens and 2,4-dibromoestradiol, an effective estrogen 2-hydroxylase inhibitor, in male rat liver microsomes resulted in Dixon plots consisting of a series of parallel lines. Thus, methoxyestrogens and 2,4-dibromoestradiol are mutually exlusive inhibitors, i.e., the binding of one compound to the enzyme interferes with the binding of the other. These results indicate that the compounds are interacting at the same enzymatic site. Finally, a method utilized to measure estrogen 2-hydroxylase activity in vitro is a radioenzymatic assay involving addition of catechol o-methyltransferase (COMT) and radiolabeled S-adenosylmethionine, and the amount of catechol estrogens formed is determined by the amount of radiolabeled methoxyestrogens isolated. The results described here demonstrate inhibition of estrogen 2-hydroxylase by methoxyestrogens; however, under enzymatic conditions of low product formation, the estrogen 2-hydroxylase inhibitory effect of catechol estrogen products from the radioenzymatic assay would be insignificant. Thus, these interactions of methoxyestrogens suggest that the steroid hormonal environment be considered in the examination of estrogen 2-hydroxylase and the catechol estrogen products. |
| abstract_unstemmed |
The inhibition of estrogen 2-hydroxylase by 2-methoxyestrogens was demonstrated in screening assays and has been further investigated under initial velocity conditions. The ability of 2-methoxyestradiol and 2-methoxyestrone to block the conversion of estradiol to 2-hydroxyestradiol by male rat liver microsomal preparations was determined by measuring the release of ^3H"2O from [2-^3H]estradiol. The apparent K"is were found to be 34.86 μM for 2-methoxyestradiol and 18.65μM for the methoxyestrone, with the apparent K"m for the substrate estradiol in these essays of 3.21 μM. Mixed inhibition studies with the methoxyestrogens and 2,4-dibromoestradiol, an effective estrogen 2-hydroxylase inhibitor, in male rat liver microsomes resulted in Dixon plots consisting of a series of parallel lines. Thus, methoxyestrogens and 2,4-dibromoestradiol are mutually exlusive inhibitors, i.e., the binding of one compound to the enzyme interferes with the binding of the other. These results indicate that the compounds are interacting at the same enzymatic site. Finally, a method utilized to measure estrogen 2-hydroxylase activity in vitro is a radioenzymatic assay involving addition of catechol o-methyltransferase (COMT) and radiolabeled S-adenosylmethionine, and the amount of catechol estrogens formed is determined by the amount of radiolabeled methoxyestrogens isolated. The results described here demonstrate inhibition of estrogen 2-hydroxylase by methoxyestrogens; however, under enzymatic conditions of low product formation, the estrogen 2-hydroxylase inhibitory effect of catechol estrogen products from the radioenzymatic assay would be insignificant. Thus, these interactions of methoxyestrogens suggest that the steroid hormonal environment be considered in the examination of estrogen 2-hydroxylase and the catechol estrogen products. |
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