Resonance Raman spectra of bc 1 complexes and isolated c 1 subunit from Rhodobacter capsulatus have been obtained using a variety of excitation wavelengths. Spectra obtained via Q-band excitation of bc 1 complexes in different redox states were separated to yield the individual vibrational spectra of each of the three heme active sites. Hemes b H and c 1 exhibit vibrational spectra typical of b-and c-type hemes, respectively. In contrast, the spectrum of heme b L is anomalous with respect to

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... se of other hemes b. The isolated spectra were also used to assess the effects of inhibitor binding on the local structural environments of the hemes. Neither antimycin nor myxothiazol binding produces dramatic structural perturbations at the hemes. Heme c 1 is completely unaffected by the presence of either inhibitor. The vibrational spectra of hemes b H and b L are slightly altered by antimycin and myxothiazol binding, respectively.