title: Esters of 5-carboxyl-5-methyl-1-pyrroline N-oxide: a family of spin traps for superoxide.
abstract: Apparent rate constants, at acidic pH and neutral pH for the reaction of a family of ester-containing 5-carboxyl-5-methyl-1-pyrroline N-oxides with superoxide (O2*-) were estimated, using ferricytochrome c as a competitive inhibitor. It was of interest to note that the rate constants were similar among the different nitrones and not that significantly different from that found for 5-(diethoxyphosphoryl)-5-dimethyl-1-pyrroline N-oxide. At acidic pH, the rate constant for spin trapping O2*- was 3-fold greater than that at physiological pH. Subsequent experiments determined the half-life of aminoxyls, derived from the reaction of these nitrones with O2*-. The EPR spectra were modeled by using a global analysis method. The results clearly demonstrated that EPR spectra of all the aminoxyls were inconsistent with a model that included a single gamma-hydrogen splitting. A better interpretation modeled them as two diastereomers with identical nitrogen splittings and slightly different beta-hydrogen splittings. Detailed line width analyses slightly favored an equal line width-unequal population ratio for the two diastereomers.
mesh_terms: D001667:Binding, Competitive; D003497:Cyclic N-Oxides / Q000737:chemistry*; D045304:Cytochromes c / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D004952:Esters / Q000737:chemistry*; D006207:Half-Life; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011758:Pyrroles / Q000737:chemistry*; D013113:Spin Labels; D019097:Spin Trapping; D013481:Superoxides / Q000032:analysis / Q000737:chemistry*; D019820:Xanthine / Q000737:chemistry; D014969:Xanthine Oxidase / Q000737:chemistry
chemical_list: D003497:Cyclic N-Oxides; D004952:Esters; D011758:Pyrroles; D013113:Spin Labels; D013481:Superoxides; D019820:Xanthine; C013231:pyrroline; D045304:Cytochromes c; D014969:Xanthine Oxidase