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Peroxynitrite

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Peroxynitrite
Peroxynitrite-ion-2D.png
Chemical structure of the peroxynitrite anion
Names
IUPAC name
Oxido nitrite
Identifiers
3D model (JSmol)
ChEBI
KEGG
PubChem CID
UNII
  • InChI=1S/HNO3/c2-1-4-3/h3H/p-1
    Key: CMFNMSMUKZHDEY-UHFFFAOYSA-M
  • N(=O)O[O-]
Properties
NO3
Molar mass 62.005 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Reactions of peroxynitrite leading to either apoptotic or necrotic cell death

Peroxynitrite (sometimes called peroxonitrite) is an ion with the formula ONOO. It is a structural isomer of nitrate, NO
3

Preparation

Peroxynitrite can be prepared by the reaction of superoxide with nitric oxide:

NO + O2 → NO(O2)

It is prepared by the reaction of hydrogen peroxide with nitrite:

H2O2 + NO
2
→ ONOO + H2O

Its presence is indicated by the absorbance at 302 nm (pH 12, ε302 = 1670 M−1 cm−1).

Reactions

Peroxynitrite is weakly basic with a pKa of ~6.8.

It is reactive toward DNA and proteins.

ONOO reacts nucleophilically with carbon dioxide. In vivo, the concentration of carbon dioxide is about 1 mM, and its reaction with ONOO occurs quickly. Thus, under physiological conditions, the reaction of ONOO with carbon dioxide to form nitrosoperoxycarbonate (ONOOCO
2
) is by far the predominant pathway for ONOO. ONOOCO
2
homolyzes to form carbonate radical and nitrogen dioxide, again as a pair of caged radicals. Approximately 66% of the time, these two radicals recombine to form carbon dioxide and nitrate. The other 33% of the time, these two radicals escape the solvent cage and become free radicals. It is these radicals (carbonate radical and nitrogen dioxide) that are believed to cause peroxynitrite-related cellular damage.

Peroxynitrous acid

Its conjugate acid peroxynitrous acid is highly reactive, although peroxynitrite is stable in basic solutions.

See also


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