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Topography of tyrosine residues and their involvement in peroxidation of polyunsaturated cardiolipin in cytochrome c/cardiolipin peroxidase complexes.
Kapralov AA; Yanamala N; Tyurina YY; Castro L; Samhan-Arias A; Vladimirov YA; Maeda A; Weitz AA; Peterson J; Mylnikov D; Demicheli V; Tortora V; Klein-Seetharaman J; Radi R; Kagan VE
Biochim Biophys Acta 2011 Sep; 1808(9):2147-2155
Formation of cytochrome c (cyt c)/cardiolipin (CL) peroxidase complex selective toward peroxidation of polyunsaturated CLs is a pre-requisite for mitochondrial membrane permeabilization. Tyrosine residues - via the generation of tyrosyl radicals (Tyr) - are likely reactive intermediates of the peroxidase cycle leading to CL peroxidation. We used mutants of horse heart cyt c in which each of the four Tyr residues was substituted for Phe and assessed their contribution to the peroxidase catalysis. Tyr67Phe mutation was associated with a partial loss of the oxygenase function of the cyt c/CL complex and the lowest concentration of H(2)O(2)-induced Tyr radicals in electron paramagnetic resonance (EPR) spectra. Our MS experiments directly demonstrated decreased production of CL-hydroperoxides (CL-OOH) by Tyr67Phe mutant. Similarly, oxidation of a phenolic substrate, Amplex Red, was affected to a greater extent in Tyr67Phe than in three other mutants. Tyr67Phe mutant exerted high resistance to H(2)O(2)-induced oligomerization. Measurements of Tyr fluorescence, hetero-nuclear magnetic resonance (NMR) and computer simulations position Tyr67 in close proximity to the porphyrin ring heme iron and one of the two axial heme-iron ligand residues, Met80. Thus, the highly conserved Tyr67 is a likely electron-donor (radical acceptor) in the oxygenase half-reaction of the cyt c/CL peroxidase complex.
Cytology; Cytochemistry; Cell-alteration; Cell-function; Cell-metabolism; Peroxidases; Iron-compounds; Oxidation; Oxidative-processes; Simulation-methods; Spectroscopes; Animals; Myocardium; Mutation; Metabolism; Membrane-filters; Hydroperoxides; Phenyls; Heart; Free-radical-generation; Free-radicals; Author Keywords: Cytochrome c; Cardiolipin; Tyrosine; Cardiolipin hydroperoxide; Peroxidase
Valerian E. Kagan, Center for Free Radical and Antioxidant Health, Department of Environmental and Occupational Health, University of Pittsburgh, Bridgeside Point 100 Technology Drive, Suite 350, Pittsburgh, PA, USA
7439-89-6; 55520-40-6; 7722-84-1; 7782-44-7
Issue of Publication
Biochimica et Biophysica Acta
University of Pittsburgh at Pittsburgh