Figure 3. Ferric reduction by ascorbate for adult and fetal Hb.

Ferric (met) Hb (10 µM) was reacted with ascorbate in 70 mM sodium phosphate buffer, pH 7.2 and reduction of metHb to oxyHb monitored optically and rate constants were determined by fitting to a single exponential function. (A) Example of absorbance spectra under conditions indicated. (B) Rates of ferric reduction at high and low concentrations of ascorbate for A1 (dark gray) and F1 (light gray).