Biological consequences of fatty acid oxygenase reaction mechanisms

Fatty acid oxygenases catalyze the insertion of molecular oxygen into polyunsaturated fatty acids. The enzymic reactions that have been studied in detail exhibit a continuous requirement for a hydroperoxide activator and appear to proceed by a free radical chain reaction. The self-limiting nature of fatty acid oxygenase-catalyzed reactions appears to be due to enzyme self-inactivation during the reaction rather than to product inhibition. Thus "suicide" substrates are potential regulators of overall enzyme activity, although linoleate is a much weaker inactivator than the highly unsaturated fatty acids. Inhibition by added glutathione peroxidase has demonstrated the need for hydroperoxide activator in the cyclooxygenase reaction catalyzed by prostaglandin H synthase and the lipoxygenase reactions catalyzed by lung, leukocyte, and soybean enzyme preparations. The regulation of cellular hydroperoxide levels may influence the formation of prostaglandins and other autacoids by fatty acid oxygenases.