title: Photoaffinity labeling of an antimycin-binding site in Rhodopseudomonas sphaeroides.
abstract: Tritium-labeled 3-azidosalicyl-N-(n-octadecyl)amide was synthesized and used as a photoaffinity probe for the antimycin-binding site in both purified ubiquinone-cytochrome b-c1 oxidoreductase and chromatophore vesicles from the photosynthetic bacterium Rhodopseudomonas sphaeroides. In both systems, a prominently labeled protein had a molecular weight of 11,000. Binding to this protein was inhibited by preincubation of the reaction mixture with antimycin prior to addition of the radioactive analog and subsequent irradiation. The antimycin analog, 3-azidosalicyl-N-(n-octadecyl)amide, inhibited succinate-cytochrome c reductase activity in chromatophore vesicles by 50% at a concentration of 150 nmols/mg of protein.
authors.forename: E
authors.initials: E
authors.lastname: Wilson
authors.forename: T M
authors.initials: TM
authors.lastname: Farley
authors.forename: J Y
authors.initials: JY
authors.lastname: Takemoto
mesh_terms: D000345:Affinity Labels / Q000378:metabolism*; D000968:Antimycin A / Q000031:analogs & derivatives* / Q000378:metabolism; D001386:Azides / Q000138:chemical synthesis / Q000378:metabolism*; D020130:Bacterial Chromatophores / Q000378:metabolism; D001665:Binding Sites; D014450:Electron Transport Complex III; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000302:isolation & purification / Q000378:metabolism; D011808:Quinone Reductases / Q000302:isolation & purification / Q000378:metabolism; D012242:Rhodobacter sphaeroides / Q000378:metabolism*; D013384:Succinate Cytochrome c Oxidoreductase / Q000037:antagonists & inhibitors
chemical_list: D000345:Affinity Labels; D001386:Azides; D009097:Multienzyme Complexes; C032456:antimycin; D000968:Antimycin A; C046280:3-azidosalicyl-N-(n-octadecyl)amide; D013384:Succinate Cytochrome c Oxidoreductase; D011808:Quinone Reductases; D014450:Electron Transport Complex III