Protein N-Acylation: H sub(2)O sub(2)-Mediated Covalent Modification of Protein by Lipid Peroxidation-Derived Saturated Aldehydes

• Published in: Chemical research in toxicology 2008-01, Vol.21 (6), p.1261-1270
• Main Authors: Ishii, Takeshi, Toyokuni, Shinya, Sayre, Lawrence M, Zhu, Xiaochun, Ishino, Kousuke, Liu, Yu-Ting, Shibata, Takahiro, Uchida, Koji
• Format: Article
• Language: English
• ISSN: 0893-228X; 1520-5010
• DOI: 10.1021/tx800080x

Various lines of evidence indicate that the oxidative modification of protein and the subsequent accumulation of the degenerated proteins have been found in cells and tissues during aging, oxidative stress, and in a variety of pathological states. The critical agents that give rise to this protein degeneration may be represented by aldehydes. Although the covalent modification of proteins by aldehydes alone has been well-studied, the effect of reactive oxygen species, such as H sub(2)O sub(2), upon aldehyde modification of the protein has received little attention. We have now established a unique protein modification in which H sub(2)O sub(2) and, to a lesser extent, alkyl hydroperoxides mediate the binding of alkanals to the lysine residues of protein to generate structurally unusual N-acylation products. Upon the reaction of a lysine-containing peptide, N super( alpha )-benzoylglycyl-lysine, with hexanal in the presence of H sub(2)O sub(2), a product containing one molecule of hexanal per peptide was detected. On the basis of the chemical and spectroscopic evidence, the product was identified to be the acylation product, N super( epsilon )-hexanoyllysine. H sub(2)O sub(2) mediated the N-acylation of the lysine derivative by the saturated aldehydes of 1-6 carbons in length. The H sub(2)O sub(2)-mediated acylation of the protein was immunochemically confirmed by reaction of the proteins with hexanal in the presence of H sub(2)O sub(2). Furthermore, the enhanced N-acylations (N-acetylation and N-hexanoylation) were also observed in the kidney of rats exposed to ferric nitrilotriacetate, a well-characterized inducer of oxidative stress. Mechanistic studies using a phosphonium lysine derivative suggest a Baeyer-Villiger-like reaction proceeding through peroxide addition to the aldehyde Schiff base. These data suggest that the hydroperoxides, including H sub(2)O sub(2), might be involved not only in the oxidative modification of protein but also in the covalent binding of the saturated aldehydes to proteins under oxidative stress.