title: The assignment of the 655 nm spectral band of cytochrome oxidase.
abstract: The spectral characteristics of the '655 nm' band of cytochrome oxidase were found to be affected by ligands of the binuclear centre, including formate and chloride, and by the resting/pulsed transition. The band titrated with near n = 1 characteristics at a midpoint of about 400 mV, in contrast to haem a3, which exhibits strong redox interaction and a titration range at significantly lower potential. Thus, although the total reduced-oxidised difference spectrum of haem a3 shows a trough at about 655 nm, this characteristic is absent in the low potential region. The 655 nm feature may arise from a charge transfer band of ferric high-spin haem a3, which is modulated by the redox state of CuB, as suggested by Beinert et al. [(1976) Biochim. Biophys. Acta 423, 339-355].
authors.affiliation: Glynn Research Institute, Bodmin, UK.
authors.forename: R
authors.initials: R
authors.lastname: Mitchell
authors.forename: P
authors.initials: P
authors.lastname: Mitchell
authors.forename: P R
authors.initials: PR
authors.lastname: Rich
mesh_terms: D000818:Animals; D002417:Cattle; D002712:Chlorides / Q000737:chemistry; D003300:Copper / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000378:metabolism; D005561:Formates / Q000737:chemistry; D006418:Heme / Q000031:analogs & derivatives / Q000737:chemistry; D008024:Ligands; D009206:Myocardium / Q000201:enzymology; D010084:Oxidation-Reduction; D013053:Spectrophotometry
chemical_list: D002712:Chlorides; D005561:Formates; D008024:Ligands; C030544:formic acid; C027728:heme a; D006418:Heme; D003300:Copper; D003576:Electron Transport Complex IV