Spin trapping of glutathiyl and protein radicals produced from nitric oxide-derived oxidants.
Despite the importance of protein radicals in cell homeostasis and cell injury, their formation, localization, and propagation reactions remain obscure, mainly because of the difficulties in detecting and characterizing radicals, in general, and protein radicals, in particular. New approaches based on spin trapping coupled with other methodologies are under development/testing but so far they have been applied mainly to the study of protein-tyrosyl and protein-tryptophanyl radicals. Here, our aim is to emphasize the importance of developing new methodologies for the detection of glutathyil and protein-cysteinyl radicals under physiological conditions. To this end, we summarize current EPR evidence supporting the view that glutathione and protein-cysteines are among the preferential targets of nitric oxide-derived oxidants and that they are oxidized to the glutathiyl and protein-cysteinyl radicals, respectively. The possible intermediacy of these species in the biological formation of mediators of protein-cysteine redox signaling, such as S-nitrosothiols and sulfenic acids, is also discussed.
Augusto
Ohara
O
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CP 26077, CEP 05599-970, São Paulo, SP, Brazil. oaugusto@iq.usp.br
Bonini
Marcelo G
MG
Trindade
DanielF
D
D000818:Animals; D003497:Cyclic N-Oxides; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry / Q000378:metabolism; D005978:Glutathione / Q000032:analysis*; D006801:Humans; D009569:Nitric Oxide / Q000737:chemistry*; D016877:Oxidants / Q000378:metabolism; D011506:Proteins / Q000032:analysis*; D013113:Spin Labels; D019097:Spin Trapping; D014443:Tyrosine / Q000737:chemistry
D003497:Cyclic N-Oxides; D005609:Free Radicals; D016877:Oxidants; D011506:Proteins; D013113:Spin Labels; C408694:tyrosine radical; D009569:Nitric Oxide; D014443:Tyrosine; D005978:Glutathione