Lipid peroxidation affects catalytic properties of rat liver mitochondrial monoamine oxidases and their sensitivity to proteolysis.

1. Lipid peroxidation (LPO) in rat liver mitochondria decreased the activity of monoamine oxidase (MAO) with physiological substrates serotonin and 2-phenylethylamine (by 15-30%) and induced deamination of glucosamine, which was highly sensitive to selective MAO A inhibitor pirlindole. 2. The LPO-induced changes in catalytic properties of MAOs are accompanied by their increased susceptibility to trypsinolysis, however sensitivity to inhibition by imipramine, chlorpromazine and spermine are insignificantly changed. 3. It is suggested that these results reflect LPO-induced conformational changes of enzyme molecules in membrane rather than their membrane topography.