Association of spin-labelled cardiolipin with dimyristoylphosphatidylcholine-substituted bovine heart cytochrome c oxidase. A generalized specificity increase rather than highly specific binding sites.
The endogeneous lipid of bovine heart cytochrome c oxidase has been replaced by dimyristoylphosphatidylcholine using cholate-mediated exchange. The lipid-substituted preparation contained less than 1 mole cardiolipin per mole enzyme and possessed full oxidative activity. The association of spin-labelled cardiolipin with such lipid-substituted cytochrome oxidase preparations has been assayed using ESR spectroscopy. An average relative association constant 5.4-times that for phosphatidylcholine is obtained for cardiolipin. Measurements on preparations with increasing contents of unlabelled cardiolipin, introduced during lipid exchange, reveal that this selectivity corresponds to a generalized increase in specificity for all lipid association sites on the protein.
Powell
G L
GL
Knowles
P F
PF
Marsh
D
D
D000818:Animals; D001665:Binding Sites; D002308:Cardiolipins / Q000378:metabolism*; D002417:Cattle; D004134:Dimyristoylphosphatidylcholine / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D003576:Electron Transport Complex IV / Q000378:metabolism*; D050356:Lipid Metabolism; D009206:Myocardium / Q000201:enzymology*; D011485:Protein Binding; D013113:Spin Labels
D002308:Cardiolipins; D013113:Spin Labels; D003576:Electron Transport Complex IV; D004134:Dimyristoylphosphatidylcholine