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To evaluate their usefulness as chemical indicators of cumulative oxidative damage to proteins, we studied the kinetics and extent of formation of ortho-tyrosine (0-Tyr), dityrosine (DT), and dityrosine-like fluorescence (Ex = 3 17 nm, E,,, = 407 nm) in the model proteins RNase and lysozyme exposed to radiolytic and metalcatalyzed (H20z/Cu2+) oxidation (MCO). Although there were protein-dependent differences, o-Tyr, DT, and fluorescence increased coordinately during oxidation of the proteins in both oxidation systems. The contribution of DT to total dityrosine-like fluorescence in oxidized proteins varied from 2-10070, depending on the protein, type of oxidation, and extent of oxidative damage. In proteins exposed to MCO, DT typically accounted for >50% of the fluorescence at DT wavelengths. These studies indicate that o-Tyr and DT should be useful chemical markers of cumulative exposure of proteins to MCO in vitro and in vivo.


This research was originally published in the Journal of Biological Chemistry. Huggins TG, Wells-Knecht MC, Detorie NA, Baynes JW, Thorpe SR. Formation of o-Tyrosine and Dityrosine in Proteins during Radiolytic and Metal-catalyzed Oxidation. Journal of Biological Chemistry. 1993, 268:12341-12347. © the American Society for Biochemistry and Molecular Biology

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