Resonance Raman spectra of cytochromes c and b in Paracoccus denitrificans membranes: evidence for heme--heme interactions.

Resonance Raman (RR) scattering from cytochromes b and c in the bacterium Paracoccus denitrificans was recorded by exciting with the 568.2-, 530.9-, and 520.8-nm lines of a Kr+ laser. The main features of the spectra were similar to those of the analogous cytochrome b-c1 complex derived from pigeon breast mitochondria. Differences in the 1300-cm-1 region were interpreted in terms of marker bands for heme type and spectral coupling of the hemes on the membranes. It is difficult to explain the results without invoking sharing of electronic and vibrational wave functions among the hemes. This conclusion documents the potential to study the physics of electron transport in functioning membrane by monitoring the RR spectra.