Resonance Raman spectra of whole mitochondria

The resonance Raman spectra of reduced cytochromes b and c and cytochrome oxidase in whole mitochondria have been recorded without any instrument modifications. The contributions of the individual cytochromes have been identified by comparison with the characteristic features observed in partially purified preparations including: (i) the strong dependence of the intensity patterns on excitation wavelength relative to the peak positions of the alpha, beta, and gamma absorption bands of the cytochromes; and (ii) the presence of marker bands for heme type. Since the Raman spectra can be used as an intrinsic indicator of interaction between hemes, the ability to record spectra in intact mitochondria opens the possibility to study heme-heme interactions in the functioning membrane in situ.