Immunochemical study on the pathway of electron flow in reduced nicotinamide adenine dinucleotide-dependent microsomal lipid peroxidation.
NADH could support the lipid peroxidation of rat liver microsomes in the presence of ferric ions chelated by ADP(ADP-Fe). The reaction had a broad pH optimum (pH 5.8--7.4) and was more active in the acidic pH range. Antibodies to NADH-cytochrome b5 reductase [EC 1.6.2.2] and cytochrome b5 inhibited NADH-dependent lipid peroxidation in the presence of ADP-Fe, whereas the antibody against NADPH-cytochrome c reductase [EC 1.6.2.4] showed no inhibition. These oberservations suggest that the electron from NADH was supplied to the lipid peroxidation reaction via NADH-cytochrome b5 reductase and cytochrome b5. On the other hand, NADPH-supported lipid peroxidation was strongly inhibited by the antibody against NADPH-cytochrome c reductase, confirming the participation of this this flavoprotein in the NADPH-dependent reaction. In the presence of both ADP-Fe and ferric ions chelated by EDTA(EDTA-Fe), NADH-dependent lipid peroxidation was highly stimulated up to the level of the NADPH-dependent reaction. In this case, the antibody against cytochrome b5 could not inhibit the reaction, while the antibody against NADH-cytochrome b5 reductase did inhibit it, suggesting the direct transfer of electrons from NADH-cytochrome b5 reductase to EDTA-Fe complex.
D000818:Animals; D000918:Antibody Specificity; D003579:Cytochrome Reductases / Q000276:immunology / Q000378:metabolism; D003580:Cytochromes / Q000276:immunology; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000494:pharmacology; D050356:Lipid Metabolism; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D008862:Microsomes, Liver / Q000378:metabolism*; D009243:NAD / Q000494:pharmacology*; D010545:Peroxides / Q000378:metabolism*; D051381:Rats
D003580:Cytochromes; D010545:Peroxides; D009243:NAD; D008315:Malondialdehyde; D007501:Iron; D003579:Cytochrome Reductases