Chemistry:Peroxynitrite
Peroxynitrite (sometimes called peroxonitrite) is an ion with the formula ONOO−. It is a structural isomer of nitrate, NO−3. Peroxynitrite is a potent reactive nitrogen species and is highly cytotoxic.[1]
Preparation
Peroxynitrite can be prepared by the reaction of superoxide with nitric oxide:[2][3][4]
- NO + O−
2 → NO(O
2)−
It is prepared by the reaction of hydrogen peroxide with nitrite:[5]
- 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.[6] 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.[7][8]
See also
References
- ↑ Szabó, Csaba; Ischiropoulos, Harry; Radi, Rafael (August 2007). "Peroxynitrite: biochemistry, pathophysiology and development of therapeutics" (in en). Nature Reviews Drug Discovery 6 (8): 662–680. doi:10.1038/nrd2222. ISSN 1474-1784. https://www.nature.com/articles/nrd2222.
- ↑ Bohle, D. Scott; Sagan, Elisabeth S. (2004). "Main Group Compounds". Tetramethylammonium Salts of Superoxide and Peroxynitrite. Inorganic Syntheses. 34. pp. 36. doi:10.1002/0471653683.ch1. ISBN 978-0-471-64750-8.
- ↑ Pacher, P; Beckman, J. S; Liaudet, L (2007). "Nitric oxide and peroxynitrite in health and disease". Physiological Reviews 87 (1): 315–424. doi:10.1152/physrev.00029.2006. PMID 17237348.
- ↑ Szabó, C; Ischiropoulos, H; Radi, R (2007). "Peroxynitrite: Biochemistry, pathophysiology and development of therapeutics". Nature Reviews Drug Discovery 6 (8): 662–80. doi:10.1038/nrd2222. PMID 17667957.
- ↑ Beckman, J. S; Koppenol, W. H (1996). "Nitric oxide, superoxide, and peroxynitrite: The good, the bad, and ugly". American Journal of Physiology. Cell Physiology 271 (5 Pt 1): C1424–37. doi:10.1152/ajpcell.1996.271.5.C1424. PMID 8944624.
- ↑ Denicola, Ana; Freeman, Bruce A.; Trujillo, Madia; Radi, Rafael (1996-09-01). "Peroxynitrite Reaction with Carbon Dioxide/Bicarbonate: Kinetics and Influence on Peroxynitrite-Mediated Oxidations". Archives of Biochemistry and Biophysics 333 (1): 49–58. doi:10.1006/abbi.1996.0363. ISSN 0003-9861. https://www.sciencedirect.com/science/article/pii/S000398619690363X.
- ↑ Holleman, A. F.; Wiberg, E. Inorganic Chemistry Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- ↑ Koppenol, W. H (1998). "The chemistry of peroxynitrite, a biological toxin". Química Nova 21 (3): 326–331. doi:10.1590/S0100-40421998000300014.
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