Figure 8.

Oxidation of Fe³⁺cyt c to M-Fe³⁺cyt c by HOCl increases the initial rate of formation of superoxide radical adducts of DMPO (DMPO-OOH). The preparation of M-Fe³⁺cyt c is described in the materials and methods section. EPR spin trapping experiments were performed with DMPO (50 mM), methyl-β-cyclodextrin (0.1 M), Fe³⁺cyt c/M-Fe³⁺cyt c (0.1 mM), NADH (1 mM), and H₂O₂ (0.5 mM) in phosphate buffer containing DTPA (0.1 mM). A: Fe³⁺cyt c. B: M-Fe³⁺cyt c. EPR spectra were quantified by computer simulation of the spectra and comparison of the double integral of the observed signal with that of a TEMPO standard (1 µM) measured under the identical conditions. Initial rates were calculated and mean ± S.E shown in graph (n = 3).