Figure 5.

Estimation of purple complex before and after H₂O₂ treatment. Reaction mixtures contained various amounts of Fz, FeSO₄, and histidine, and reactions were initiated as described in the legend of Fig. 1. Immediately after the 10-min spectra were recorded, 30 mM H₂O₂ was added and the spectra were recorded again. The amount of purple complex present after the 10-min incubation period was calculated from the spectra obtained immediately before and after the H₂O₂ addition on the basis of Eqs. 3 and 2, respectively, as described in Experimental Procedures.