FIGURE 4.
EPR spectra of the cyt bc1 complex [2Fe-2S] clusters (upper panel) and the cyt b hemes (lower panel) of R. capsulatus MT-G4/S4 lacking cyt c2 and pYO38/YO2 containing a cyt bc1-cy fusion complex with a native cyt cy linker, as described in the legend to Fig. 2. For EPR spectroscopy of the [2Fe-2S] cluster or cyt b hemes (bL and bH), chromatophore membranes were reduced with ascorbate or air oxidized, respectively, as described in Refs. 35 and 36. Spectra were recorded at 20 K, 9.443 GHz, 12 G and 10 K, 9.59 GHz, 10 G temperature, microwave frequencies, and modulation amplitudes, respectively.