ИСТИНА

Interaction of cytochrome c (cyt c) with cardiolipin converts this electron-transfer protein into peroxidase, suggested to be involved in apoptosis initiation. Liposome membrane permeabilization provoked by peroxidase activity of the cyt c/cardiolipin complex has been previously shown to be suppressed by such antioxidants as trolox, butylated hydroxytoluene and quercetin. Here, the mitochondria-targeted antioxidants SkQ1 and MitoQ, representing conjugates of a lipophilic triphenylphosphonium cation with decylplastoquinone and decylubiquinone, respectively, were found to markedly inhibit both the cyt c/H2O2-induced permeabilization of cardiolipin-containing liposomes and cyt c/cardiolipin peroxidase activity, as monitored by the Amplex Red assay. Examination of the cyt c binding to liposomes by monitoring cyt c absorbance and quenching of pyrene-labeled lipid fluorescence revealed an inhibiting effect of both SkQ1 and MitoQ on the cyt c binding, thus suggesting that SkQ1- and MitoQ-mediated protection of liposomes from the cyt c/H2O2-induced permeabilization involved distortion of the cyt c-membrane interaction.