Fig. 6. Thermodynamic behavior of the b-type hemes in H6B strain (his-tagged cyt b with wild-type sequence) in situ.

(Top left) typical titration data in the absence and presence of antimycin (pH 7); (bottom left) spectra from redox cuts showing cyt b₁₅₀, heme b_H and heme b_L; the dashed line shows the curve expected for an n=1 component, with amplitude for degree of reduction plotted as $\mathrm{\Delta }A=0.055\frac{1}{{10}^{(E_h-E_m)/59}+1}$ (Bottom, right) spectra derived by fitting titrations at each wavelength using fixed values for E_m, and n, for each component; (top, right) the pH-dependence of E_m values for individual components, assuming single species for each component.