Electronic and vibrational spectroscopy of the cytochrome c: Cytochrome c oxidase complexes from bovine and Paracoccus denitrificans

Abstract

The 1: 1 complex between horse heart cytochrome c and bovine cytochrome c oxidase, and between yeast cytochrome c and Paracoccus denitrificans cytochrome c oxidase have been studied by a combination of second derivative absorption, circular dichroism (CD), and resonance Raman spectroscopy. The second derivative absorption and CD spectra reveal changes in the electronic transitions of cytochrome a upon complex formation. These results could reflect changes in ground state heme structure or changes in the protein environment surrounding the chromophore that affect either the ground or excited electronic states. The resonance Raman spectrum, on the other hand, reflects the heme structure in the ground electronic state only and shows no significant difference between cytochrome a vibrations in the complex or free enzyme. The only major difference between the Raman spectra of the free enzyme and complex is a broadening of the cytochrome a3 formyl band of the complex that is relieved upon complex dissociation at high ionic strength. These data suggest that the differences observed in the second derivative and CD spectra are the result of changes in the protein environment around cytochrome a that affect the electronic excited state. By analogy to other protein-chromophore systems, we suggest that the energy of the Soret "K* state of cytochrome a may be affected by (1) changes in the local dielectric, possibly brought about by movement of a charged amino acid side chain in proximity to the heme group, or (2) T-"K interactions between the heme and aromatic amino acid residues.

Red LED Light Acts on the Mitochondrial Electron Chain of Donkey Sperm and Its Effects Depend on the Time of Exposure to Light

“…With regard to the effects of red light on the mitochondrial electron chain observed in this work, it is reasonable to surmise that this could be explained by the direct action of red light on mitochondrial photosensitizers (reviewed in Yeste et al, 2018). Indeed, we observed that red light affected the activity of CCO, which is a crucial component of the mitochondrial electron chain and is sensitive to light at a wavelength ranging from 630 to 660 nm (Lynch and Copeland, 1992). These observed FIGURE 8 | Effects of light-stimulation on cytochrome C oxidase activity in the presence/absence of either oligomycin A (Omy A) or FCCP.…”

“…Motile sperm subpopulations were determined through the protocol described in Luna et al (2017). In brief, individual kinematic parameters (VCL, VSL, VAP, LIN, STR, WOB, ALH, and BCF) recorded for each sperm cell were used as independent variables in a Principal Component Analysis (PCA).…”

“…Cytochromes have a heme group, which not only accepts and donates electrons ( Kessel, 1982 ; Pottier and Truscott, 1986 ), but is sensitive to light. However, not all cytochromes react against the same wavelengths ( Lynch and Copeland, 1992 ). Thus, whereas cytochrome P450, which is also present in the endoplasmic reticulum of somatic cells, has its highest absorption peak at 450 nm, cytochrome C, which forms the complex IV of the mitochondrial electron chain, has two peaks at 610–630 nm and 660–680 nm ( Lynch and Copeland, 1992 ).…”

Probing protein‐cofactor interactions in the terminal oxidases by second derivative spectroscopy: Study of bacterial enzymes with cofactor substitutions and heme a model compounds

“…Toward this end, we have introduced the use of second derivative absorption spectroscopy as a means of resolving and studying the individual electronic transitions of the 2 heme groups within the protein (Copeland, 1991(Copeland, , 1993Ishibe et al, 1991;Sherman et al, 1991;Lynch & Copeland, 1992;Lynch et al, 1992). During the course of these studies we have discovered a new electronic transition of one of the hemes at ca.…”

“…We have previously shown that the double Soret transition of ferrocytochrome a collapses to a single band at 443 nm when ferrocytochrome c is bound to the enzyme at the CU, site of subunit I1 (Lynch & Copeland, 1992;Lynch et al, 1992). Li et al (1988) and Nilsson et al (1988) have shown that mild heat treatment of the bovine enzyme selectively disrupts the structure around CU,.…”