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Radiation chemical experiments demonstrate that the reaction of tyrosyl radical (TyrO(.)) with (.)NO(2) yields 45 +/- 3% 3-nitrotyrosine and that a major product of the reaction of TyrO(.) with (.)NO is 3,3'-dityrosine. Radiolysis was used to generate (.)NO and O-(2) in the presence of tyrosine and bicarbonate at pH 7.5 +/- 0.1. The nitration yield was(More)
Numerous transition metal ions and their complexes in their lower oxidation states (LmMn+) were found to have the oxidative features of the Fenton reagent, and, therefore, the mixtures of these metal compounds with H2O2 were named "Fenton-like" reagents. Using the Marcus theory and the experimental data in the literature, it is shown that in most cases the(More)
The reactions of NO. with O2.- and with HO2. were studied using the pulse radiolysis technique under pseudo first order conditions where ([O2.-]o + [HO2.]o) > [NO.]o at pH 3.3-10.0. The rate constant of the reaction of NO. with O2.- was determined both by monitoring the decay of O2.- at 250 nm and the formation of ONOO- at 302 nm to be (4.3 +/- 0.5) x 10(9)(More)
We have studied the reaction kinetics of ten manganese porphyrins, differing in their meso substituents, with peroxynitrite (ONOO-) and carbonate radical anion (CO3.) using stopped-flow and pulse radiolysis, respectively. Rate constants for the reactions of Mn(III) porphyrins with ONOO- ranged from 1 x 10(5) to 3.4 x 10(7) m(-1) s(-1) and correlated well(More)
In this study we calculate the half-life of .NO in its reactions with superoxide and with oxygen under various conditions using the known rate constants for these reactions. The measured half-life of .NO in biological systems is 3-5 s, which agrees well with the calculated value for intracellular .NO, but not for extracellular .NO under normal physiological(More)
The kinetics and the reaction mechanism of some copper complexes of l,IO-phenanthroline, 5-nitrc1, IO-phenanthroline, and 2,2’-bipyridine with 02-, Hz02, and O2 in the presence of calf thymus DNA have been investigated with use of the pulse radiolysis technique. We have found that both copper(I1) and copper(1) complexes bind to DNA. The ternary complexes(More)
Nitric oxide reacts slowly with ONOO- (k < 1.3 x 10(-)3 M-1 s-1), and therefore does not affect the stability of peroxynitrite at pH >12. A chain consumption of peroxynitrite by *NO takes place at pH <12 through the reaction of N2O3 with ONOO-, where the former is formed through two initiation steps: (i) autoxidation of *NO, which is the main process in(More)
In a recent publication (Michel et al. Arch. Biochem. Biophys. 439:234-240; 2005) the authors argued that the catalytic rate constant, k(cat), for wild-type Cu,Zn-superoxide dismutase (Cu,Zn-SOD), determined previously by pulse radiolysis, was overestimated due to contamination with excess copper. They reported that addition of 0.1 mM EDTA to a sample that(More)
The method of determination of Redox potentials of radicals, using the pulse radiolysis technique, is outlined. The method is based on the determination of equilibrium constants of electron transfer reactions between the radicals and appropriate acceptors. The limitations of this technique are discussed. The redox potentials of several quinones-semiquinones(More)