S-nitrosation of glutathione by nitric oxide, peroxynitrite, and (*)NO/O(2)(*-).
To elucidate potential mechanisms of S-nitrosothiol formation in vivo, we studied nitrosation of GSH and albumin by nitric oxide ((*)NO), peroxynitrite, and (*)NO/O(2)(*)(-). In the presence of O(2), (*)NO yielded 20% of S-nitrosoglutathione (GSNO) at pH 7.5. Ascorbate and the spin trap 4-hydroxy-[2,2,4,4-tetramethyl-piperidine-1-oxyl] (TEMPOL) inhibited GSNO formation by 67%. Electron paramagnetic resonance spectroscopy with 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) demonstrated intermediate formation of glutathionyl radicals, suggesting that GSNO formation by (*)NO/O(2) is predominantly mediated by (*)NO(2). Peroxynitrite-triggered GSNO formation (0.06% yield) was stimulated 10- and 2-fold by ascorbate and TEMPOL, respectively. Co-generation of (*)NO and O(2)(*)(-) at equal fluxes yielded less GSNO than (*)NO alone, but was 100-fold more efficient (8% yield) than peroxynitrite. Moreover, in contrast to the reaction of peroxynitrite, GSNO formation by (*)NO/O(2)(*)(-) was inhibited by ascorbate. Similar results were obtained with albumin instead of GSH. We propose that sulfhydryl compounds react with O(2)(*)(-) to initiate a chain reaction that forms radical intermediates which combine with (*)NO to yield GSNO. In RAW 264.7 macrophages, S-nitrosothiol formation by (*)NO/O(2) and (*)NO/O(2)(*)(-) occurred with relative efficiencies comparable to those in solution. Our results indicate that concerted generation of (*)NO and O(2)(*)(-) may essentially contribute to nitrosative stress in inflammatory diseases.
Schrammel
Astrid
A
Institut für Pharmakologie und Toxikologie, Karl-Franzens-Universität Graz, Graz, Austria.
Gorren
Antonius C F
AC
Schmidt
Kurt
K
Pfeiffer
Silvia
S
Mayer
Bernd
B
D000418:Albumins / Q000378:metabolism; D001205:Ascorbic Acid / Q000737:chemistry; D003497:Cyclic N-Oxides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D005978:Glutathione / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008264:Macrophages / Q000378:metabolism; D008956:Models, Chemical; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D015538:Nitrosation; D010100:Oxygen / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012235:Rhodamines / Q000494:pharmacology; D026422:S-Nitrosoglutathione / Q000737:chemistry; D013113:Spin Labels; D013997:Time Factors
D000418:Albumins; D003497:Cyclic N-Oxides; D005609:Free Radicals; D020030:Nitric Oxide Donors; D017382:Reactive Oxygen Species; D012235:Rhodamines; D013113:Spin Labels; C058319:dihydrorhodamine 123; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D005978:Glutathione; D001205:Ascorbic Acid; D010100:Oxygen; C001803:tempol