1H-n.m.r. evaluation of the ferricytochrome c-cardiolipin interaction. Effect of superoxide radicals

The interaction between ferricytochrome c and cardiolipin was investigated by 1H n.m.r. at 270 MHz. From the phospholipid-induced changes of the protein spectral features it is concluded that the first 2 equivalents of cardiolipin cause a conformational change at the lower part of the solvent-expose...

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Bibliographic Details
Published in:Biochemical journal 1990-01, Vol.265 (1), p.227-232
Main Authors: Soussi, B, Bylund-Fellenius, A C, Scherstén, T, Angström, J
Format: Article
Language:English
Subjects:
Animals
Cardiolipins - metabolism
Cytochrome c Group - metabolism
Free Radicals
Horses
Magnetic Resonance Spectroscopy
Myocardium - enzymology
Protein Conformation
Superoxides - metabolism
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Summary:The interaction between ferricytochrome c and cardiolipin was investigated by 1H n.m.r. at 270 MHz. From the phospholipid-induced changes of the protein spectral features it is concluded that the first 2 equivalents of cardiolipin cause a conformational change at the lower part of the solvent-exposed haem edge, involving a rearrangement of the hydrogen-bond interactions of propionate 6, thus partly accounting for the lowered redox potential of cytochrome c in the presence of cardiolipin. The increased value for the pK of the alkaline isomerization of ferricytochrome c shows that cardiolipin stabilizes the native structure of the protein, indicating that the oxidized form assumes ferrocytochrome c-like properties. Peroxidation of cardiolipin by superoxide radical ions drastically decreases the protein binding to this phospholipid. The implications of this finding, and the likelihood of the ternary cytochrome c-cardiolipin-cytochrome c oxidase complex, for the binding of cytochrome c to cytochrome c oxidase in vivo, are discussed in relation to peroxidative damage following ischaemia and reperfusion.
ISSN:0264-6021
1470-8728
DOI:10.1042/bj2650227