Figure 5.

Role of cardiolipin-derived lipid hydroperoxide reduction on cyt c peroxidase activity and enzyme degradation. In A, peroxidase activity measurements were performed in the absence (black) of lipid or in the presence of liposomes (500 μm lipid concentration) containing nonreduced (red) or reduced (violet) TLCL by incubating 5 μm cyt c without (dashed) or with (straight) 25 μm H₂O₂ for 180 min in 10 mm PB at 37 °C. ABTS radical formation from 1 mm ABTS was monitored at 734 nm. The strong peroxidase activity–promoting effects of TLCL both in the absence and presence of H₂O₂ are considerably inhibited by previous reduction of the LOOH amount. As shown in B, the H₂O₂-independent TLCL-derived heme degradation in cyt c is also considerably disturbed by reducing the LOOH amount. Averaged kinetic curves from three independent experiments are displayed.