Investigation of effect of oxidative stress on proteomic signatures in diseases

In diseases such as breast cancer, diabetes and Parkinson\u27s disease the antioxidant defense system is overwhelmed by excessive oxidative stress (OS) leading to protein oxidation. This research established the effect of OS on proteomic signatures for the path of destruction that excessive levels of OS leave behind. This change in the proteomic signatures was established at the recombinant protein level, in animal model and in humans. The work described here started with reporting the first proteomic based identification and characterization of oxidized proteins in human plasma. Sixty five high, medium, and low abundance proteins were identified, the majority appearing in all subjects. Twenty four oxidative modifications were mapped in fourteen proteins. For the first time oxidation products arising from direct ROS oxidation of amino acid side chains in proteins, formation of advanced glycation endproducts (AGEs) adducts, and formation of adducts with lipid peroxidation products (ALEs) were simultaneously recognized and assigned to specific sites in proteins. Analysis of breast cancer patients indicated the differential change of 97 oxidized proteins in the plasma of 6 patients compared to their control. The function of these proteins were related to the cancer biology (e.g. immunity, DNA binding, DNA helicase). On the other hand, the concentration of four proteins and eleven carbonylation sites changed significantly in the plasma of type II diabetic rats versus their controls. Then a novel method was developed for the assessment of the impact of antioxidant supplementation on OS in vivo. This is based on the site, extent, and type of OS initiated post-translational modification (OSi∼PTM) in plasma proteins. The major effect of green tea on the OS proteomic signature in type II diabetes was on the AGEs followed by ALEs followed by direct carbonylation. Finally, the OS proteomic signature for the effect of the pathogenic M26I mutation on the Parkinson\u27s protective protein, DJ-1 was characterized. This mutation reduced the oxidation of a key residue which may have reduced the chaperonic activity of this protein