Oxidative damage of lysozyme and human serum albumin and their mixtures: a comparison of photosensitized and peroxyl radical promoted processes.

Oxidative modifications of lysozyme (Lyso) and human serum albumin (HSA) mediated by photoinduced processes and peroxyl radicals were studied. Both oxidative conditions were applied to the separate proteins and their mixtures. Dimerization and fragmentation of the proteins do not correlate with the formation of carbonyls or peroxides, implying that evaluation of these changes is not an index of the overall oxidative modification of a protein. The results obtained also show that the hypothesis that the electrostatic interactions of Lyso and HSA could facilitate the formation of Lyso-HSA dimers in the presence of a source of reactive oxygen species was verified in both ROS-producing systems.