Interaction of cotinine with rat hepatic microsomal P-450. Comparison with metyrapone and immunomodulation of cotinine and metyrapone binding by monoclonal anti-cotinine antibodies
| Autor: | R J, Bjercke, D K, Hammond, H W, Strobel, J J, Langone |
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| Rok vydání: | 1990 |
| Předmět: |
Antibodies
Monoclonal Enzyme-Linked Immunosorbent Assay Rats Inbred Strains In Vitro Techniques Metyrapone Rats Kinetics Spectrometry Fluorescence Cytochrome P-450 Enzyme System Enzyme Induction Phenobarbital Cytochrome P-450 CYP2B1 Microsomes Liver Animals Cytochrome P-450 Enzyme Inhibitors Cotinine Oxidoreductases |
| Zdroj: | Drug metabolism and disposition: the biological fate of chemicals. 18(5) |
| ISSN: | 0090-9556 |
| Popis: | The ability of the major nicotine metabolite, cotinine, to interact with rat liver microsomal cytochrome P-450 and the immunomodulatory effects of anti-cotinine antibodies were studied. Cotinine induced type II spectral changes with both microsomes from phenobarbital (PB)-induced rats and purified P-450 with apparent Ks values of 97 and 750 microM, respectively. In contrast, the Ks value was 0.3 microM for metyrapone and 5 microM for nicotine with both the microsomes and purified enzyme. The apparent Ki value for cotinine inhibition of 7-pentoxyresorufin O-dealkylase activity with the microsomes (87 microM) was approximately 87- and 870-fold higher than for nicotine and metyrapone, respectively. Monoclonal antibodies produced against cotinine cross-reacted equally well with metyrapone. They specifically blocked enzyme binding of both drugs based on dose-dependent inhibition of spectral changes, and reversed the metyrapone-induced inhibition of microsomal O-dealkylase activity. In contrast, antibodies to nicotine did not cross-react with cotinine or metyrapone and had no effect on their activity, although they did block the action of nicotine. These results demonstrate that cotinine binding to P-450 from PB-induced rats and inhibition of functional activity in vitro are qualitatively like the effects of metyrapone and nicotine, and that monoclonal anti-cotinine antibodies are useful molecular probes of the interactions between cotinine and metyrapone with the enzyme. |
| Databáze: | OpenAIRE |
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