title: Photoinduced intracomplex electron transfer between cytochrome c oxidase and TUPS-modified cytochrome c.
abstract: A novel method for initiating intramolecular electron transfer in cytochrome c oxidase is reported. The method is based upon photoreduction of cytochrome c labeled with thiouredopyrene-3,6, 8-trisulfonate in complex with cytochrome oxidase. The thiouredopyrene-3,6,8-trisulfonate-labeled cytochrome c was prepared by incubating the thiol reactive form of the dye with yeast iso-1-cytochrome c, containing a single cysteine residue. Laser pulse excitation of a stoichiometrical complex between thiouredopyrene-3,6,8-trisulfonate-cytochrome c and bovine heart cytochrome oxidase at low ionic strength resulted in the reduction of cytochrome c by the excited form of thiouredopyrene-3,6, 8-trisulfonate and subsequent intramolecular electron transfer from the reduced cytochrome c to cytochrome oxidase. The maximum efficiency by a single laser pulse resulted in the reduction of approximately 17% of cytochrome a, and was achieved only at a 1 : 1 ratio of cytochrome c to cytochrome oxidase. At higher cytochrome c to cytochrome oxidase ratios the heme a reduction was strongly suppressed.
authors.affiliation: Department of Biochemistry, Tel Aviv University, Ramat Aviv Israel, sasha@hemi.tau.ac.il
authors.forename: A
authors.initials: A
authors.lastname: Kotlyar
authors.forename: N
authors.initials: N
authors.lastname: Borovok
authors.forename: M
authors.initials: M
authors.lastname: Hazani
authors.forename: I
authors.initials: I
authors.lastname: Szundi
authors.forename: O
authors.initials: O
authors.lastname: Einarsdóttir
mesh_terms: D000818:Animals; D001400:Azurin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002374:Catalase / Q000494:pharmacology; D002417:Cattle; D004396:Coloring Agents / Q000494:pharmacology*; D003545:Cysteine / Q000737:chemistry; D003574:Cytochrome c Group / Q000737:chemistry / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000378:metabolism*; D004583:Electrons; D005947:Glucose / Q000494:pharmacology; D005949:Glucose Oxidase / Q000494:pharmacology; D006418:Heme / Q000378:metabolism; D007700:Kinetics; D008027:Light; D009206:Myocardium / Q000201:enzymology; D011721:Pyrenes; D013053:Spectrophotometry; D013997:Time Factors
chemical_list: D004396:Coloring Agents; D003574:Cytochrome c Group; D011721:Pyrenes; C121436:thiouredopyrenetrisulfonate; D001400:Azurin; D006418:Heme; D005949:Glucose Oxidase; D002374:Catalase; D003576:Electron Transport Complex IV; D005947:Glucose; D003545:Cysteine