Reactions of the bioregulatory agent nitric oxide in oxygenated aqueous media: determination of the kinetics for oxidation and nitrosation by intermediates generated in the NO/O2 reaction

Chem Res Toxicol. 1993 Jan-Feb;6(1):23-7. doi: 10.1021/tx00031a003.

Abstract

The reaction kinetics of nitric oxide autoxidation in aerobic solutions were investigated by direct observation of the nitrite ion product and by trapping the strongly oxidizing and nitrosating intermediates formed in this reaction. The rate behavior observed for nitrite formation [rate = k3[O2][NO]2, k3 = (6 +/- 1.5) x 10(6) M-2 s-1 at 22 degrees C] was the same as found for oxidation of Fe(CN)6(4-) and of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and as for the nitrosation of sulfanilamide. There was a slight decrease in k3 to (3.5 +/- 0.7) x 10(6) M-2 s-1 at 37 degrees C. The second-order dependency for NO was observed at NO concentrations as low as 3 microM. The results of the competitive kinetics studies suggest that the key oxidizing intermediates, species which are both strong oxidants and nitrosating agents, are not one of those commonly proposed (NO2, N2O3, NO+, or O2NO-) but are one or more as yet uncharacterized NOx species.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aerobiosis
  • Benzothiazoles
  • Diazonium Compounds / chemistry
  • Ferrocyanides / chemistry
  • Gases
  • Kinetics
  • Nitric Oxide / chemistry*
  • Nitroso Compounds / chemistry
  • Oxidation-Reduction
  • Oxygen / chemistry*
  • Solutions
  • Spectrophotometry, Ultraviolet
  • Sulfanilamides / chemistry
  • Sulfonic Acids

Substances

  • Benzothiazoles
  • Diazonium Compounds
  • Ferrocyanides
  • Gases
  • Nitroso Compounds
  • Solutions
  • Sulfanilamides
  • Sulfonic Acids
  • 2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid
  • Nitric Oxide
  • Oxygen