monodehydroascorbate has been researched along with peroxynitric-acid* in 2 studies
2 other study(ies) available for monodehydroascorbate and peroxynitric-acid
| Article | Year |
|---|---|
Dielectric resonator-based flow and stopped-flow EPR with rapid field scanning: A methodology for increasing kinetic information.
We report methodology which combines recently developed dielectric resonator-based, rapid-mix, stopped-flow EPR (appropriate for small, aqueous, lossy samples) with rapid scanning of the external (Zeeman) magnetic field where the scanning is preprogrammed to occur at selected times after the start of flow. This methodology gave spectroscopic information complementary to that obtained by stopped-flow EPR at single fields, and with low reactant usage, it yielded more graphic insight into the time evolution of radical and spin-labeled species. We first used the ascorbyl radical as a test system where rapid scans triggered after flow was stopped provided "snapshots" of simultaneously evolving and interacting radical species. We monitored ascorbyl radical populations either as brought on by biologically damaging peroxynitrite oxidant or as chemically and kinetically interacting with a spectroscopically overlapping nitroxide radical. In a different biophysical application, where a spin-label lineshape reflected rapidly changing molecular dynamics of folding spin-labeled protein, rapid scan spectra were taken during flow with different flow rates and correspondingly different times after the mixing-induced inception of protein folding. This flow/rapid scan method is a means for monitoring early immobilization of the spin probe in the course of the folding process. Topics: Antioxidants; Cytochrome c Group; Cytochromes c; Dehydroascorbic Acid; Electron Spin Resonance Spectroscopy; Free Radicals; Magnetics; Nitrates; Nitrogen Oxides; Oxidants; Protein Folding; Pulsatile Flow; Saccharomyces cerevisiae Proteins; Spin Labels | 1999 |
Generation of thiyl and ascorbyl radicals in the reaction of peroxynitrite with thiols and ascorbate at physiological pH.
Electron spin resonance (ESR) spin trapping was utilized to investigate the reaction of peroxynitrite with thiols and ascorbate at physiological pH. The spin trap used was 5,5-dimethyl-1-pyrroline N-oxide (DMPO). The reaction of peroxynitrite with DMPO generated 5,5-dimethylpyrrolidone-(2)-oxy-(1) (DMPOX). Formate enhanced the peroxynitrite decomposition but did not generate any detectable amount of formate-derived free radicals. Thus, the spin trapping measurements provided no evidence for hydroxyl (.OH) radical generation in peroxynitrite decomposition at physiological pH. Thiols (glutathione, cysteine, and penicillamine) and ascorbate reacted with peroxynitrite to generate the corresponding thiyl and ascorbyl radicals. The one-electron oxidation of thiols by peroxynitrite may be one of the important mechanisms for peroxynitrite-induced toxicity and ascorbate may provide a detoxification pathway. Topics: Ascorbic Acid; Cyclic N-Oxides; Dehydroascorbic Acid; Electron Spin Resonance Spectroscopy; Free Radicals; Hydrogen-Ion Concentration; Models, Biological; Nitrates; Spin Labels; Sulfhydryl Compounds | 1994 |