Mechanism-based inhibition of mouse P4502b-10 by selected arylalkynes
| Autor: | William L. Alworth, Laura W. Fornwald, Paul F. Hollenberg, Elizabeth S. Roberts, Lisa E. Beebe |
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| Rok vydání: | 1996 |
| Předmět: |
Male
Cytochrome In Vitro Techniques Naphthalenes Biochemistry Mice Cytochrome P-450 Enzyme System Microsomes Oxazines Animals Cytochrome P-450 Enzyme Inhibitors Enzyme Inhibitors Cytochrome P450 Family 2 Lung Pharmacology chemistry.chemical_classification Unspecific monooxygenase biology Active site Cytochrome P450 Phenanthrenes Rats Kinetics Enzyme chemistry Enzyme inhibitor Suicide inhibition Alkynes Steroid Hydroxylases Microsomes Liver biology.protein Microsome Aryl Hydrocarbon Hydroxylases |
| Zdroj: | Biochemical Pharmacology. 52:1507-1513 |
| ISSN: | 0006-2952 |
| Popis: | Suicide inhibitors of cytochrome P450 families are excellent tools to predict which isoforms mediate the metabolism/activation of a variety of chemical agents. We compared the inhibitory effects of several arylalkynes on mouse cytochromes P450 with published data for the rat model. The inhibition of P4502b specific dealkylation of benzyloxyresorufin by 2-ethynylnaphthalene (2-EN), 5-phenyl-1-pentyne (PPY), 4-phenyl-1-butyne (PBY), and 9-ethynylphenanthrene (9-EPh) was measured in hepatic microsomes from male mice treated with 1,4-bis[2-(3,5-dichloropyridyloxy)]-benzene (TCPOBOP) to induce cytochrome P4502b. Pulmonary microsomes were prepared from untreated mice. 9-EPh, 2-EN, and PPY caused a time-, concentration-, and NADPH-dependent loss in P4502b activity in both tissues. PBY, however, demonstrated this type of inhibition only in liver microsomes. The ic 50 was calculated for both liver and lung microsomes and compared with published K i (concentration required for half-maximal inhibition) or K I (concentration required for halfmaximal inactivation) values for the rat. PPY, PBY, and 9-EPh were equally effective inhibitors of mouse P4502b and rat P4502B1. 2-EN was a 5- to 10-fold less potent inhibitor of mouse P4502b, as compared with the rat, even though it was shown to bind to the active site of the mouse isoform as demonstrated by its metabolism to 2-naphthylacetic acid. These data suggest that the active site of the mouse P4502b enzyme is functionally similar to the rat P4502B isoform, with the exception of the disparity in its susceptibility to inactivation by 2-EN as measured by the K i ; values. |
| Databáze: | OpenAIRE |
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