title: Photoperturbation of the heme a3-CuB binuclear center of cytochrome c oxidase CO complex observed by Fourier transform infrared spectroscopy.
abstract: Purified cytochrome c oxidase CO complex from beef heart has been studied by Fourier transform infrared absorbance difference spectroscopy. Photolysis at 10-20 Kelvin results in dissociation of a3FeCO, formation of CuBCO, and perturbation of the a3-heme and CuB complex. The vibrational perturbation spectrum between 900 and 1700 cm-1 contains a wealth of information about the binuclear center. Appearance in infrared photoperturbation difference spectra of virtually all bands previously reported from resonance Raman spectra indicate the importance of polarization along the 4-vinyl:8-formyl axis, which results in the reduction of heme symmetry to C2v. Frequency-shifted bands due to the 8-formyl and 4-vinyl groups of the a3-heme have been identified and quantitated. The frequency shifts have been interpreted as being due to a change in porphyrin polarization with change in spin state of the iron by photodissociation of CO or perturbation of the CuB coordination complex.
authors.affiliation: Department of Medical Biochemistry, Ohio State University, Columbus 43210, USA.
authors.forename: S
authors.initials: S
authors.lastname: Park
authors.forename: L P
authors.initials: LP
authors.lastname: Pan
authors.forename: S I
authors.initials: SI
authors.lastname: Chan
authors.forename: J O
authors.initials: JO
authors.lastname: Alben
mesh_terms: D000818:Animals; D002248:Carbon Monoxide / Q000378:metabolism*; D002417:Cattle; D003300:Copper / Q000032:analysis / Q000378:metabolism*; D003624:Darkness; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000378:metabolism*; D006418:Heme / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D008027:Light; D046911:Macromolecular Substances; D008929:Mitochondria, Heart / Q000201:enzymology; D008961:Models, Structural; D010777:Photochemistry; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods
chemical_list: D046911:Macromolecular Substances; C027728:heme a; D006418:Heme; D003300:Copper; D002248:Carbon Monoxide; D003576:Electron Transport Complex IV