The mechanism of initiation of lipid peroxidation. Evidence against a requirement for an iron(II)-iron(III) complex.
When Fe2+ ions are added to rat-liver microsomes, lipid peroxidation begins after a short lag period. Fe2+-dependent peroxidation in the first few minutes of the incubation can be increased by adding Fe3+, ascorbic acid or Pb2+ ions; these stimulations are not additive. By contrast, Pb2+ ions inhibit peroxidation of microsomes in the presence of Fe3+/ascorbate or Fe3+-ADP/NADPH. In liposomes made from ox-brain phospholipids, Fe2+-dependent peroxidation is stimulated slightly by Fe3+, but much more so by ascorbic acid, Al3+ or Pb2+; these stimulations are not additive. Liposomal peroxidation in the presence of Fe3+/ascorbate is inhibited by Pb2+ or Al3+. These results argue against the participation of an Fe2+-Fe3+-O2 complex, or a critical 1:1 ratio of Fe2+ to Fe3+, in the initiation of lipid peroxidation in liposomes and rat-liver microsomes.
Aruoma
O I
OI
Department of Biochemistry, University of London King's College, Strand, U.K.
Halliwell
B
B
Laughton
M J
MJ
Quinlan
G J
GJ
Gutteridge
J M
JM
D000535:Aluminum / Q000378:metabolism; D000818:Animals; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism*; D007854:Lead / Q000378:metabolism; D008054:Lipid Peroxides / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism; D008862:Microsomes, Liver / Q000378:metabolism*; D051381:Rats
D008054:Lipid Peroxides; D008081:Liposomes; D007854:Lead; D000535:Aluminum; D007501:Iron