Figure 3. Light-induced, time-resolved single turnover cytochrome c re-reduction and cytochrome b reduction kinetics of R. capsulatus.
Chromatophore membranes of R. capsulatus containing 0.28 μM reaction center were resuspended in 50 mM MOPS buffer (pH 7.0)/100 mM KCl (A) or 50 mM Glycine-NaOH buffer (pH 9.5)/100 mM KCl/10 μM myxothiazol (B) with appropriate mediators (see “Materials and Methods”). For the forward reaction, the redox potentials were poised at 100 mV where the Qpool is half-reduced and -oxidized at pH 7.0 (A) or at 125 mV where the Qpool is fully oxidized at pH 9.5 (B) for the reverse reaction. Spectral changes were monitored at 550 minus 540 nm and 560 minus 570 nm for the cytochrome c re-reduction and cytochrome b reduction following a short (8 μs) flash of light, respectively.