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. Author manuscript; available in PMC: 2007 Mar 21.
Published in final edited form as: Free Radic Biol Med. 2006 Nov 10;42(3):404–412. doi: 10.1016/j.freeradbiomed.2006.11.007

Figure 3.

Figure 3

The kinetics of the reduction of 0.1 mM nitroxide 3 (A) and 1 mM nitroxide 1 (B) by 50 mM ascorbate in the presence of various concentrations of corresponding HA, 3H and 1H, measured by EPR spectroscopy (see Materials and Methods). The solutions were prepared in deaerated 0.1 M Na-phosphate buffer, pH 7.6, 0.1 mM DTPA. The concentrations of the hydroxylamines for the kinetics from bottom to top were 0, 0.1, and 0.5 mM for 3H and 0, 2, 5, and 10 mM for 1H. Note: 0.5 mM solution of 3H contained 0.036 mM radical admixture resulted in an increase of initial concentration of the radical. For 1H the radical admixture was less than 0.1%. Lines are the best fits of the experimental data to the equations (1-4) with parameters: k1 = (0.1±0.01) M−1s−1, k−1 = (1.1±0.2)×103 M−1s−1, k2 = (1±0.2)×10−2 M−1s−1, k−2 = (0.9±0.2)×103 M−1s−1, k3 = (2.6±0.3)×106, k−3 = (1.0±0.2)×10−2 M−1s−1, k4 = (7±2)×10−4 s−1.