Modification of bovine serum albumin structure following reaction with 4,5(E)-epoxy-2(E)-heptenal

Bovine serum albumin (BSA) was incubated for different periods of time and in the presence of several concentrations of 4,5(E)-epoxy-2(E)-heptenal, at pH 7.4 and 37 degrees C, in an effort to analyze the changes produced in its structure as a consequence of its reaction with this product of lipid oxidation. The epoxyalkenal modified the primary structure of BSA as determined by lysine losses and formation of oxidative stress product epsilon-N-pyrrolylnorleucine (Pnl), which depended on the concentration of the aldehyde and the incubation time. These changes also modified secondary and tertiary structures of the protein, which were determined by studying protein denaturation and polymerization. In addition, all these modifications were parallel to the development of color and fluorescence, which were produced as a consequence of the formation and polymerization of pyrrole amino acid residues. The above results indicated that epoxyalkenals modify the protein structure and develop color and fluorescence. A failure in the degradation of these modified proteins might induce their accumulation and, thus, participation in lipofuscin or age pigments formation.