4-Hydroperoxy-2-nonenal Is Not Just an Intermediate but a Reactive Molecule That Covalently Modifies Proteins to Generate Unique Intramolecular Oxidation Products
Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan. Journal of Biological Chemistry
(Impact Factor: 4.57).
06/2011; 286(33):29313-24. DOI: 10.1074/jbc.M111.255737
α,β-Unsaturated aldehydes generated during lipid peroxidation, such as 4-oxoalkenals and 4-hydroxyalkenals, can give rise to protein degeneration in a variety of pathological states. Although the covalent modification of proteins by these end products has been well studied, the reactivity of unstable intermediates possessing a hydroperoxy group, such as 4-hydroperoxy-2-nonenal (HPNE), with protein has received little attention. We have now established a unique protein modification in which the 4-hydroperoxy group of HPNE is involved in the formation of structurally unusual lysine adducts. In addition, we showed that one of the HPNE-specific lysine adducts constitutes the epitope of a monoclonal antibody raised against the HPNE-modified protein. Upon incubation with bovine serum albumin, HPNE preferentially reacted with the lysine residues. By employing N(α)-benzoylglycyl-lysine, we detected two major products containing one HPNE molecule per peptide. Based on the chemical and spectroscopic evidence, the products were identified to be the N(α)-benzoylglycyl derivatives of N(ε)-4-hydroxynonanoic acid-lysine and N(ε)-4-hydroxy-(2Z)-nonenoyllysine, both of which are suggested to be formed through mechanisms in which the initial HPNE-lysine adducts undergo Baeyer-Villiger-like reactions proceeding through an intramolecular oxidation catalyzed by the hydroperoxy group. On the other hand, using an HPNE-modified protein as the immunogen, we raised a monoclonal antibody against the HPNE-modified protein and identified one of the HPNE-specific lysine adducts, N(ε)-4-hydroxynonanoic acid-lysine, as an intrinsic epitope of the monoclonal antibody. Furthermore, we demonstrated that the HPNE-specific epitopes were produced not only in the oxidized low density lipoprotein in vitro but also in the atherosclerotic lesions. These results indicated that HPNE is not just an intermediate but also a reactive molecule that could covalently modify proteins in biological systems.
Available from: Jody Ullery
- "This initiates a series of radical chain reactions, resulting in the formation of lipid hydroperoxides , intramolecular rearrangement and chain-breaking reactions. The peroxidation of membrane lipids containing ω-3 and/or ω-6 polyunsaturated fatty acids results in the formation of several classes of reactive aldehydes, including malondialdehyde (MDA), acrolein, and 4-hydroxy- alkenals45678. Some of the aldehydes are not cleared from the cell and exhibit cytotoxic effects91011. "
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