Evidence for superoxide radical production in peroxynitrite decomposition.
Peroxynitrite decomposition was investigated by ESR spin trapping. The spin trap used was 5,5-dimethyl-1-pyrroline N-oxide (DMPO). A mixture of peroxynitrite and DMPO generated predominantly DMPO-O2- adduct. A combination of SOD and catalase suppressed the formation of DMPO-O2-. The DMPO-O2- signal reached its maximum at pH lower than 7 and decreased as pH increased. The DMPO-O2- signal also depended on peroxynitrite concentration with maximum signal intensity appearing at 4.2 mM. The results demonstrate that peroxynitrite decomposition generates O2.-. Since reaction of H2O2 with NO2- generates peroxynitrite, the results point out a pathway for conversion of H2O2 to O2.- via peroxynitrite as an intermediate.
Zang
L Y
LY
Laboratory of Experimental Pathology, National Cancer Institute, NIH, Bethesda, MD 20892-0041, USA.
Shi
X
X
D003497:Cyclic N-Oxides; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry*; D010084:Oxidation-Reduction; D013113:Spin Labels; D019097:Spin Trapping; D013481:Superoxides / Q000737:chemistry*
D003497:Cyclic N-Oxides; D005609:Free Radicals; D009566:Nitrates; D013113:Spin Labels; D013481:Superoxides; C039642:peroxynitric acid; C017245:5,5-dimethyl-1-pyrroline-1-oxide