Structural Characterization and Immunochemical Detection of a Fluorophore Derived from 4-Hydroxy-2-Nonenal and Lysine

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 95; no. 14; pp. 7975 - 7980
• Main Authors: Tsai, Lin, Szweda, Pamela A., Vinogradova, Olga, Szweda, Luke I.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 07.07.1998; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: Adducts; Aldehydes - chemistry; Aldehydes - immunology; Animals; Antibodies; Atoms; Biochemistry; Biological Sciences; Cellular biology; Cross-Linking Reagents; Enzyme linked immunosorbent assay; Female; Fluorescence; Fluorescent Dyes - chemistry; Gels; Immunization; Immunoassay - methods; Lipids; Lysine - chemistry; Lysine - immunology; Polyclonal antibodies; Rabbits
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.95.14.7975

Aging and the progression of certain degenerative diseases are accompanied by increases in intracellular fluorescent material, termed ``lipofuscin'' and ceroid, respectively. These pigments are observed within granules composed, in part, of damaged protein and lipid. Modification of various biomolecules by aldehyde products of lipid peroxidation is believed to contribute to lipofuscin and ceroid formation. However, little direct evidence currently exists because the structures responsible for the fluorescent, cross-linked nature of this material are not well characterized. In this study, we have identified a fluorescent product formed in the reaction of Nα-acetyllysine and 4-hydroxy-2-nonenal (HNE), a major product of lipid peroxidation and the most reactive of these compounds under physiological conditions [Esterbauer, H., Shaur, R. J. & Zollner, H. (1991) Free Radical Biol. Med. 11, 81-128]. This fluorescent compound, characterized as a 2-hydroxy-3-imino-1,2-dihydropyrrol derivative, appears to form upon oxidative cyclization of the nonfluorescent 2:1 lysine-HNE Michael adduct-Schiff base cross-link. Polyclonal antibody was raised to the Nα-acetyllysine-HNE fluorophore and found to be highly specific to the chromophore structure of the compound. This antibody has been used to conclusively demonstrate that the lysine-HNE derivative of this fluorophore forms on protein upon exposure to HNE. The results of this study therefore provide the basis for future investigations on the contribution(s) of HNE-derived fluorophore formation to lipofuscin and ceroid accumulation.