Protein Carbonylation

Abstract

Roteincarbonylation is a type of protein oxidation that can be promoted by reactive oxygen species. It usually refers to a process that forms reactive ketones or aldehydes that can be reacted by 2,4-dinitrophenylhydrazine (DNPH) to form hydrazones. Direct oxidation of side chains of lysine, arginine, proline, and threonine residues, among other amino acids, in the ''primary protein carbonylation'' reaction pro- duces DNPH detectable protein products (11, 15, 23). DNPH derivatizable protein products can also be formed in the ''secondary protein carbonylation'' reaction via the addition of aldehydes such as those generated from lipid peroxida- tion processes (14, 21). Oxidative decomposition of polyun- saturated fatty acids initiates chain reactions that lead to the formation of a variety of carbonyl species (three to nine carbons in length), the most reactive and cytotoxic being a,b-unsaturated aldehydes (4-hydroxy-trans-2-nonenal and acrolein), di-aldehydes (malondialdehyde and glyoxal), and keto-aldehydes (4-oxo-trans-2-nonenal). Although the biology of oxidative protein modifications is complex and remains incompletely defined, protein carbonylation and chemistry of the reactions that give rise to carbonyl groups have been well characterized (24). The development of the antibody against DNPH-