Role of reactive oxygen species in the generation of fluorescence by glycation

Fluorescence (excitation 360 nm, emission 454 nm) generation in glycated albumin was investigated. Antioxidants and the metal chelator desferrioxamine (DFX) were used to study the mechanism of fluorescence generation. Delipidation studies, reverse phase chromatography and scanning fluorimetry were performed to examine the nature of this fluorescence. The mechanism of action of aminoguanidine, a compound which has been shown to inhibit the formation of visible fluorescence in proteins in vitro and in vivo was investigated in relation to glycation and by comparison with compounds with structural similarities. We conclude that hydrogen peroxide, metal ions and hydroxyl radicals are involved in fluorescence generation in glycated albumin, which is largely lipid in nature, and arises through glycation, amino acid oxidation and changes in bound lipid. Our results suggest that the action of aminoguanidine is not specifically related to blocking of ketoamine groups on glycated proteins as previously suggested.