Similarities and dissimilarities in the structure-function relation between the cytochrome c oxidase from bovine heart and from Paracoccus denitrificans as revealed by FT-IR difference spectroscopy

The redox dependent changes in the cytochrome c oxidase from bovine heart w ere studied with a combined electrochemical and FT-IR spectroscopic approac h,A direct comparison to the electrochemically induced FT-IR difference spe ctra of the cytochrome c oxidase from Palacoccus denitrificans reveals diff erences in the structure and intensity of vibrational modes. These differen ces are partially attributed to interactions of subunits influencing the he me and protein modes. In the spectral regions characteristic for v(C = O) a nd v(COO-)(s/as) modes of protonated and deprotonated Asp and Glu residues, additional signals at 1736, 1602 and 1588 cm(-1) are observed. On this bas is, the possible involvement of Asp-51, a residue specifically conserved in mammalian oxidase and previously proposed to show redox depended conformat ional changes in the respective X-ray structures, is critically discussed. (C) 1999 Federation of European Biochemical Societies.