Immunochemical detection of 4-hydroxynonenal protein adducts in oxidized hepatocytes

We report here the development of an immunochemical procedure that uses an antibody specific to the 4-hydroxynonenal (HNE) moiety for the detection of HNE-protein adducts. The HNE-specific antibody was prepared by immunizing rabbits with a HNE-keyhole limpet hemocyanin conjugate and purifying the rabbit serum on an affinity gel prepared by covalent attachment of a HNE-conjugated heptapeptide. When various preparations of glyceraldehyde-3-phosphate dehydrogenase containing 0-7.0 equivalent of HNE-histidine residues per subunit were obtained by incubating samples of glyceraldehyde-3-phosphate dehydrogenase with increased amounts of HNE and subjected to immunoblotting with the HNE-specific antibody, the intensities of the blots were directly proportional to the number of HNE-histidine adducts as measured directly by amino acid analysis. Binding of the HNE-conjugated glyceraldehyde-3-phosphate dehydrogenase to the HNE-specific antibody could be completely inhibited by HNE-N-acetylhistidine, HNE-N-acetyllysine, or HNE-glutathione, suggesting that the antigenic determinant recognized by the antibody is the HNE moiety, not the HNE-amino acid conjugates, such as HNE-histidine, HNE-lysine, and HNE-cysteine. The utility of the HNE-specific antibody was demonstrated by its ability to react selectively with a number of HNE-protein adducts in immunoblot analyses of crude homogenates of rat liver hepatocytes that had been exposed to HNE or oxidative stresses with tert-butylhydroperoxide or metal-ion-catalyzed oxidation systems.