Fig. 3.

Room temperature EPR spectra of the sulfite radical adduct of DMPO, DMPO-${\mathrm{SO}}_3^{-}$. All the reactions were performed in 50 mM phosphate buffer (pH=7.4) containing 0.1 mM DTPA. Spectrum A: DMPO (0.1 M), Fe³⁺cyt c (0.1 mM), sulfite (0.5 mM), and H₂O₂ (0.1 mM). Spectrum B: DMPO (0.1 mM), sulfite (0.5 mM), and H₂O₂ (0.1 mM). Spectrum C: DMPO (0.1 M), Fe³⁺cyt c (0.1 mM), and sulfite (0.5 mM). Spectrum D: DMPO (0.1 M) and sulfite (0.5 mM). EPR instrument parameters used were as described in the Materials and Methods section. Each EPR spectrum is a single scan.