Resonance Raman spectroscopy of the cytochrome c oxidase from Paracoccus denitrificans

Resonance Raman spectra are reported for the fully reduced unliganded and cyanide-bound mixed-valence forms of the cytochrome c oxidases from bovine heart and Paracoccus denitrificans in both detergent-solubilized forms and within their natural membrane environments. Comparison of the vibrational patterns observed for these enzymes indicates that overall the heme environments are similar for both. The only major differences seen between the spectra of these two enzymes are for vibrations associated with the low-spin bis(histidine)-coordinated heme cytochrome a. The data reported here serve to further illustrate the close structural and functional relationship between these evolutionarily distant enzymes. However, the data also demonstrate specific differences between the nature of the heme-protein interactions in the cytochrome a binding pocket which may be of mechanistic importance with regard to intramolecular electron transfer in these enzymes.