One-electron oxidation pathway of thiols by peroxynitrite in biological fluids: bicarbonate and ascorbate promote the formation of albumin disulphide dimers in human blood plasma.

摘要: Recent studies have shown that peroxynitrite oxidizes thiol groups through competing one- and two-electron pathways. The pathway is mediated by the anion prevails quantitatively over one-electron pathway, which peroxynitrous acid or a reactive species derived from it. In CO2-containing fluids oxidation of thiols might follow different mechanism owing to rapid formation oxidant, nitrosoperoxycarbonate (ONOOCO2(-)). Here we present evidence in blood plasma induces disulphide cross-linked protein identified immunological (anti-albumin antibodies) biochemical criteria (peptide mapping) as dimer serum albumin. albumin did not form devoid CO2 its was enhanced ascorbate. However, analysis showed reconstituting dialysed with NaHCO3 protected against simultaneouspresence ascorbate provided further protection. Ascorbate alone protect peroxynitrite-mediated oxidation. ESR spin-trapping N-t-butyl-alpha-phenylnitrone (PBN) revealed induced thiyl radicals their intensity markedly decreased dialysis restored reconstitution NaHCO3. PBN completely inhibited dimer. Moreover, addition iron-diethyldithiocarbamate demonstrated S-nitrosothiols and/or S-nitrothiols. Our results are consistent hypothesis favours radicals, ;NO2, RSNOx. Thiyl turn, involved chain reactions oxidized disulphides.