Functional binding of cardiolipin to cytochrome c oxidase.
Bovine cytochrome c oxidase usually contains 3-4 mol of tightly bound cardiolipin per cytochrome aa3 complex. At least two of these cardiolipins are required for full electron transport activity. Without the tightly bound cardiolipin, cytochrome c oxidase has only 40-50% of its original activity when assayed in detergents that support activity, e.g., dodecyl maltoside. By measuring the restoration of electron transport activity, functional binding constants for cardiolipin and a number of cardiolipin analogues have been evaluated (Kd,app = 1 microM for cardiolipin). These binding constants agree reasonably well with direct measurement of the binding using [14C]-acetyl-cardiolipin (Kd < 0.1 microM) when the enzyme is solubilized with Triton X-100. These data are discussed in relationship to the wealth of data that is known about the association of cardiolipin with cytochrome c oxidase and the other mitochondrial electron transport complexes and transporters.
Robinson
N C
NC
Department of Biochemistry, University of Texas Health Science Center, San Antonio 78284-7760.
D000818:Animals; D001665:Binding Sites; D002308:Cardiolipins / Q000378:metabolism*; D002417:Cattle; D003902:Detergents / Q000494:pharmacology; D004317:Doxorubicin / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D003576:Electron Transport Complex IV / Q000378:metabolism*; D007700:Kinetics; D011485:Protein Binding
D002308:Cardiolipins; D003902:Detergents; D004317:Doxorubicin; D003576:Electron Transport Complex IV