Artículos de revistas
Superoxide radical protects liposome-contained cytochrome c against oxidative damage promoted by peroxynitrite and free radicals
Fecha
2009Registro en:
FREE RADICAL BIOLOGY AND MEDICINE, v.47, n.6, p.841-849, 2009
0891-5849
10.1016/j.freeradbiomed.2009.06.028
Autor
MANO, Camila M.
BARROS, Marcelo P.
FARIA, Priscila A.
PRIETO, Tatiana
DYSZY, Fabio H.
NASCIMENTO, Otaciro R.
NANTES, Iseli L.
BECHARA, Etelvino J. H.
Institución
Resumen
The effects of nitrosative species on cyt c structure and peroxidase activity were investigated here in the presence of O(2)(center dot-) and anionic and zwitterionic vesicles. Nitrosative species were generated by 3-morpholinesydnonymine (SIN1) decomposition, using cyt c heme iron and/or molecular oxygen as electron acceptor. Far-and near-UV CD spectra of SIN1-treated cyt c revealed respectively a slight decrease of a-helix content (from 39 to 34%) and changes in the tryptophan structure accompanied by increased fluorescence. The Soret CD spectra displayed a significant decrease of the positive signal at 403 nm. EPR spectra revealed the presence of a low-spin cyt c form (S = 1/2) with g(1) = 2.736, g(2) = 2.465, and g(3) = 2.058 after incubation with SIN1. These data suggest that the concomitant presence of NO(center dot) and O(2)(center dot-) generated from dissolved oxygen, in a system containing cyt c and liposomes, promotes chemical and conformational modi. cations in cyt c, resulting in a hypothetical bis-histidine hexacoordinated heme iron. We also show that, paradoxically, O(2)(center dot-) prevents not only membrane lipoperoxidation by peroxide-derived radicals but also oxidation of cyt c itself due to the ability of O(2)(center dot-) to reduce heme iron. Finally, lipoperoxidation measurements showed that, although it is a more efficient peroxidase, SIN1-treated cyt c is not more effective than native cyt c in promoting damage to anionic liposomes in the presence of tert-ButylOOH, probably due to loss of affinity with negatively charged lipids. (C) 2009 Elsevier Inc. All rights reserved.