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Universidad Pedagógica y Tecnológica de Colombia (UPTC)
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Papers by Laura Castro
Journal of Biological Chemistry, 2000
and nitric oxide (⅐NO) reaction, inhibits mitochondrial respiration and can stimulate apoptosis. ... more and nitric oxide (⅐NO) reaction, inhibits mitochondrial respiration and can stimulate apoptosis. Cytochrome c, a mediator of these two aspects of mitochondrial function, thus represents an important potential target of ONOO ؊ during conditions involving accelerated rates of oxygen radical and ⅐NO generation. Horse heart cytochrome c 3؉ was nitrated by ONOO ؊ , as indicated by spectral changes, Western blot analysis, and mass spectrometry. A dose-dependent loss of cytochrome c 3؉ 695 nm absorption occurred, inferring that nitration of a critical heme-vicinal tyrosine (Tyr-67) promoted a conformational change, displacing the Met-80 heme ligand. Nitration was confirmed by cross-reactivity with a specific antibody against 3-nitrotyrosine and by increased molecular mass compatible with the addition of a nitro-(-NO 2 ) group. Mass analysis of tryptic digests indicated the preferential nitration of Tyr-67 among the four conserved tyrosine residues in cytochrome c. Cytochrome c 3؉ was more extensively nitrated than cytochrome c 2؉ because of the preferential oxidation of the reduced heme by ONOO ؊ . Similar protein nitration patterns were obtained by ONOO ؊ reaction in the presence of carbon dioxide, whereupon secondary nitrating species arise from the decomposition of the nitroso-peroxocarboxylate (ONOOCO 2 ؊ ) intermediate. Peroxynitrite-nitrated cytochrome c displayed significant changes in redox properties, including (a) increased peroxidatic activity, (b) resistance to reduction by ascorbate, and (c) impaired support of state 4-dependent respiration in intact rat heart mitochondria. These results indicate that cytochrome c nitration may represent both oxidative and signaling events occurring during ⅐NOand ONOO ؊ -mediated cell injury.
Journal of Biological Chemistry, 2000
and nitric oxide (⅐NO) reaction, inhibits mitochondrial respiration and can stimulate apoptosis. ... more and nitric oxide (⅐NO) reaction, inhibits mitochondrial respiration and can stimulate apoptosis. Cytochrome c, a mediator of these two aspects of mitochondrial function, thus represents an important potential target of ONOO ؊ during conditions involving accelerated rates of oxygen radical and ⅐NO generation. Horse heart cytochrome c 3؉ was nitrated by ONOO ؊ , as indicated by spectral changes, Western blot analysis, and mass spectrometry. A dose-dependent loss of cytochrome c 3؉ 695 nm absorption occurred, inferring that nitration of a critical heme-vicinal tyrosine (Tyr-67) promoted a conformational change, displacing the Met-80 heme ligand. Nitration was confirmed by cross-reactivity with a specific antibody against 3-nitrotyrosine and by increased molecular mass compatible with the addition of a nitro-(-NO 2 ) group. Mass analysis of tryptic digests indicated the preferential nitration of Tyr-67 among the four conserved tyrosine residues in cytochrome c. Cytochrome c 3؉ was more extensively nitrated than cytochrome c 2؉ because of the preferential oxidation of the reduced heme by ONOO ؊ . Similar protein nitration patterns were obtained by ONOO ؊ reaction in the presence of carbon dioxide, whereupon secondary nitrating species arise from the decomposition of the nitroso-peroxocarboxylate (ONOOCO 2 ؊ ) intermediate. Peroxynitrite-nitrated cytochrome c displayed significant changes in redox properties, including (a) increased peroxidatic activity, (b) resistance to reduction by ascorbate, and (c) impaired support of state 4-dependent respiration in intact rat heart mitochondria. These results indicate that cytochrome c nitration may represent both oxidative and signaling events occurring during ⅐NOand ONOO ؊ -mediated cell injury.