Fluorescent detection of alpha-aminoadipic and gamma-glutamic semialdehydes in oxidized proteins

The oxidative modification of proteins is believed to play a critical role in the etiology and/or progression of several diseases. alpha-Aminoadipic semialdehyde (AAS) and gamma-glutamic semialdehyde (GGS) residues represent major oxidized amino acids generated in oxidized proteins. This paper describes a novel procedure for the specific and sensitive determination of AAS and GGS after their reductive amination with sodium cyanoborohydride and p-aminobenzoic acid, a fluorescence reagent, to their corresponding derivatives, followed by a high-performance liquid chromatography (HPLC) analysis. This fluorescent labeling of protein-associated aldehyde moieties is a simple and accurate technique that may be widely used to reveal increased levels of oxidatively modified proteins with reactive oxygen species during aging and disease.