51] Detection of 4-hydroxy-2-nonenol adducts following lipid peroxidation from ozone exposure

Abstract

Peroxidation of membrane lipids results in free radical-mediated fragmentation of polyunsaturated fatty acids, giving rise to various aldehydes, alkenals, and hydroxyalkenals. Many of these products are cytotoxic and their effects are proposed to be mediated by reactivity toward specific proteins. 4-Hydroxy-2-nonenal (HNE), an α, β-unsaturated aldehyde, is a major and the most cytotoxic product of lipid peroxidation. As such, HNE is likely an important mediator of free radical damage to cells. Incubation of proteins with HNE results in enzyme inactivation followed by the formation of inter- and intramolecular protein cross-links. The HNE cross-linked protein exhibits fluorescence with spectral properties similar to pigments that accumulate during the progression of certain degenerative diseases (ceroid) and aging (lipofuscin). Furthermore, the HNE cross-linked protein is resistant to proteolysis and acts as a potent noncompetitive inhibitor of the multicatalytic proteosome. Detection of the HNE-modified protein serves as an important index of free radical/lipid peroxidation-derived damage, and characterization of specific protein targets of HNE modification may identify proteins highly susceptible to oxidative modification(s).