Grantee Research Project Results
Detection and Characterization of the Electron Paramagnetic Resonance-Silent Glutathionyl-5, 5-dimethyl-1-pyrroline N-oxide Adduct Derived From Redox Cycling of Phenoxyl Radicals in Model Systems and HL-60 Cells
EPA Grant Number: U914824Title: Detection and Characterization of the Electron Paramagnetic Resonance-Silent Glutathionyl-5, 5-dimethyl-1-pyrroline N-oxide Adduct Derived From Redox Cycling of Phenoxyl Radicals in Model Systems and HL-60 Cells
Investigators: Goldman, Radoslav
Institution: University of Pittsburgh
EPA Project Officer: Lee, Sonja
Project Period: January 1, 1995 through January 1, 1996
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1995) RFA Text | Recipients Lists
Research Category: Fellowship - Biochemistry , Biology/Life Sciences , Academic Fellowships
Objective:
The objectives of this research project are to: (1) develop a novel high performance liquid chromatography (HPLC) method for the detection of an electron paramagnetic resonance (EPR)-silent 5,5-dimethyl-1-pyrroline N-oxide (DMPO) adduct of glutathionyl radicals in model systems and in cells; and (2) synthesize a sufficient quantity of the adduct for characterization by UV spectrophotometry, ionspray mass spectrometry, and 1H nuclear magnetic resonance (NMR) spectroscopy.
Approach:
The antioxidant function of glutathione includes
enzymatic reduction of hydrogen peroxide by glutathione peroxidase, and nonenzymatic
reduction
of organic radicals and reactive oxygen species. The glutathionyl S-centered
radical, formed by the nonenzymatic reduction process, is a marker of oxidative
reactions proceeding by radical mechanisms. Spin adducts of glutathionyl radicals
with the spin trap DMPO are not sufficiently stable, and can be detected only
under steady-state conditions. The UV absorption max of the adduct, 258 nm,
was indicative of a 2-(S-alkylthiyl) pyrroline N-oxide chromophore. The molecular
mass of the adduct was 418 amu. No signal for the C2 proton of the DMPO-derived
portion of the adduct was evident in its 1H NMR spectrum. The results were
consistent with the structure 2-(S-glutathionyl)-5,5-dimethyl-1pyrroline N-oxide
(GS-DMPO nitrone). We showed that this adduct accumulated in the course of
peroxidase-dependent redox cycling of phenol in the presence of glutathione
and DMPO, as well as in HL-60 cells exposed to a phenol/H2O2/DMPO reaction
mixture. The EPR-silent GS-DMPO nitrone was readily assayed by HPLC under conditions
incompatible with the detection of the GS-DMPO nitroxide by EPR. To our knowledge,
this is the first direct experimental evidence for the redox cycling of phenol
in this bone marrow-derived cell line. The method may prove useful in the study
of radical-driven oxidations of glutathione in various pathophysiological processes
associated with radical mechanisms.
Supplemental Keywords:
fellowship, phenoxyl radical, glutathione, glutathionyl radical, 5,5-dimethyl-1-pyrroline N-oxide, DMPO, spin trapping, electron paramagnetic resonance, EPR, redox cycling, liquid chromagraphy, mass spectrometry, LC-MS, nuclear magnetic resonance, NMR, HL-60 cells, nitrone., Scientific Discipline, Water, Chemical Engineering, Engineering, Chemistry, & Physics, Biochemistry, Environmental Engineering, high performance liquid chromatography, bioengineering, nuclear magnetic resonanceProgress and Final Reports:
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.