Related Experiment Video
Updated: Jul 27, 2026

Monitoring the Reductive and Oxidative Half-Reactions of a Flavin-Dependent Monooxygenase using Stopped-Flow Spectrophotometry
Published on: March 18, 2012
Polyamine effects on cytochrome P-450- and flavin-containing monooxygenase-mediated oxidation of xenobiotics
Abstract:
The effects of in vitro addition of polyamines on the female mouse hepatic microsomal cytochrome P-450- and flavin-containing monooxygenase-dependent oxidation of xenobiotics were examined. Putrescine, spermine, and spermidine all caused a different degree of stimulation of oxidative dearylation of parathion and O-ethyl-O-p-nitrophenylphosphonothioate, epoxidation of aldrin, and O-deethylation of 7-ethoxycoumarin. The degree of stimulation was greatest in the presence of spermidine. Enhancement of aldrin epoxidation by spermidine was higher in pregnant mice as compared to nonpregnant mice. Total phorate S-oxidation was stimulated by all the polyamines tested. Phorate S-oxidation, mediated by microsomal flavin-containing monooxygenase, was only slightly increased by spermine and spermidine while putrescine caused slight inhibition. Of the various steps involved in the monooxygenation cycle examined, only the rates of NADPH oxidation and cytochrome P-450 reduction were significantly increased. Efficient coupling of NADPH utilization with substrate oxidation appears to be the underlying mechanism responsible for the polyamine-stimulated xenobiotic oxidation.
More Related Videos
07:38A General Method for Detecting Nitrosamide Formation in the In Vitro Metabolism of Nitrosamines by Cytochrome P450s
Published on: September 25, 2017
09:33Formation of Covalent DNA Adducts by Enzymatically Activated Carcinogens and Drugs In Vitro and Their Determination by 32P-postlabeling
Published on: March 20, 2018
Related Concept Videos
Peroxisomes
Oxidation of Phenols to Quinones
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
Drug Metabolism: Phase I Reactions
Factors Affecting Drug Biotransformation: Physicochemical and Chemical Properties of Drugs
The drug's acidity or basicity is essential in determining the metabolic...
Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes
Bioactivation and Tissue Toxicity