
Peroxynitrite (sometimes called peroxonitrite) is an
ion with the formula ONOO
−. It is a
structural isomer of
nitrate
Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wa ...
,
Preparation
Peroxynitrite can be prepared by the reaction of
superoxide
In chemistry, a superoxide is a compound that contains the superoxide ion, which has the chemical formula . The systematic name of the anion is dioxide(1−). The reactive oxygen ion superoxide is particularly important as the product of t ...
with
nitric oxide:
:
It is prepared by the reaction of
hydrogen peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscosity, viscous than Properties of water, water. It is used as an oxidizer, bleaching agent, and antiseptic, usua ...
with
nitrite:
: H
2O
2 + → ONOO
− + H
2O
Its presence is indicated by the
absorbance at 302
nm (pH 12, ''ε''
302 = 1670 M
−1 cm
−1).
Reactions
Peroxynitrite is weakly basic with a
p''K''a of ~6.8.
It is reactive toward
DNA and
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
s.
ONOO
− reacts
nucleophilically with
carbon dioxide
Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
. ''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 () is by far the predominant pathway for ONOO
−. 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
*
Nitrotyrosine
*
Reactive nitrogen species
References
{{Nitrogen compounds
Nitrogen oxyanions
Atmospheric chemistry
Toxins