FIGURE 8.

sMF6p/FhHDM-1 protects hemin from degradation by H₂O₂. A, hemin (23 μm) was incubated with sMF6p/FhHDM-1 (unfilled circles) at protein/hemin molar ratios of 5:1 (solid blue line), 2:1 (solid green line), and 1:1 (dashed red line); BSA at a molar ratio of 5:1 (unfilled squares); or without protein (filled circles), and changes in the absorption spectra (250–700 nm) were monitored before (t = 0) and at several times within 30 min after the addition of 890 μm H₂O₂. The percentage of the initial absorbance at the Soret peak remaining in each sample after the addition of H₂O₂ was plotted against time. B–D, absorption spectra at t = 0 (black line) and t = 30 (red line) of hemin alone (B), with sMF6p/FhHDM-1 (C), and with BSA (D) at the 5:1 protein/hemin ratio. The arrows indicate the direction of the change in the absorbance at the Soret band. E and F, comparison of the absorption spectra at t = 0 (solid lines) and t = 30 (dashed lines) for hemin with sMF6p/FhHDM-1 at 5:1 (blue lines), 2:1 (green lines), and 1:1 (red lines) protein/hemin ratios (E) and of hemin alone (black lines) with sMF6p/FhHDM-1 (blue lines) and BSA (red lines) at a 5:1 ratio (F).