The non-linear dependence of cytochrome P450 activity at low microsome concentration

A non-linear decrease in the activity of cytochrome P450-dependent (P450) ethoxyphenoxazone deethylase was observed with intact rat liver and lung microsomal fractions, although all components of the P450 complex were present. Activity was restored by adding pre-heated microsomal membranes or synthe...

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Bibliographic Details
Published inBiochemistry international Vol. 15; no. 5; p. 1033
Main Authors Rabovsky, J, Judy, D J
Format Journal Article
LanguageEnglish
Published Australia 01.11.1987
Subjects
Animals
Cytochrome P-450 CYP1A1
Cytochrome P-450 Enzyme System - metabolism
Dimyristoylphosphatidylcholine - pharmacology
Kinetics
Lung - enzymology
Lung - ultrastructure
Male
Microsomes, Liver - enzymology
Oxidoreductases - metabolism
Rats
Rats, Inbred Strains
Spectrometry, Fluorescence
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Summary:A non-linear decrease in the activity of cytochrome P450-dependent (P450) ethoxyphenoxazone deethylase was observed with intact rat liver and lung microsomal fractions, although all components of the P450 complex were present. Activity was restored by adding pre-heated microsomal membranes or synthetic phospholipid, or by concentrating the diluted preparation. Aqueous dilution of the microsomal fraction resulted in altered Vmax values, whereas Km(app) values (0.2 microM) were only slightly changed. The results are discussed in terms of the relationship between cytochrome P450 action in model systems and in native microsomal membranes.
ISSN:0158-5231