Nanosecond time-resolved fluorescence investigations of temperature-induced conformational changes in cytochrome oxidase in phosphatidylcholine vesicles and solubilized systems.
Intrinsic and lipid phase transition-induced conformational changes in cytochrome oxidase in phosphatidylcholine vesicle and solubilized systems were examined by the fluorescence lifetime of N-(1-anilinonaphthyl-4)-maleimide conjugated with the enzyme. The time-dependent fluorescence intensity of N-(1-anilinonaphthyl-4)-maleimide attached to cytochrome oxidase was described as a triple exponential decay. Both the intrinsic and lipid phase transition-induced conformational changes were detectable in plots of the average lifetime against temperature. In most cases a peak occurred at the temperature of the conformational change. The time-dependent emission anisotropy showed that N-(1-anilinonaphthyl-4)-maleimide embedded in cytochrome oxidase in phosphatidylcholine vesicles underwent a rapid restricted wobbling within a cone. The half-angle of the cone was around 30 degrees for cytochrome oxidase in dimyristoyl phosphatidylcholine vesicles.
D000818:Animals; D002417:Cattle; D003576:Electron Transport Complex IV; D007700:Kinetics; D008081:Liposomes; D008301:Maleimides; D008433:Mathematics; D009206:Myocardium / Q000201:enzymology; D010713:Phosphatidylcholines; D011487:Protein Conformation; D012995:Solubility; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013997:Time Factors
D008081:Liposomes; D008301:Maleimides; D010713:Phosphatidylcholines; C010854:N-(1-anilinonaphthalyl)-4-maleimide; D003576:Electron Transport Complex IV