title: Formation of peroxynitrite from reaction of nitroxyl anion with molecular oxygen.
abstract: Peroxynitrite (ONOO(-)/ONOOH) is generally expected to be formed in vivo from the diffusion-controlled reaction between superoxide (O(2)) and nitric oxide ((*)NO). In the present paper we show that under aerobic conditions the nitroxyl anion (NO(-)), released from Angeli's salt (disodium diazen-1-ium-1,2,2-triolate, (-)ON=NO(2)(-)), generated peroxynitrite with a yield of about 65%. Simultaneously, hydroxyl radicals are formed from the nitroxyl anion with a yield of about 3% via a minor, peroxynitrite-independent pathway. Further experiments clearly underline that the chemistry of NO(-) in the presence of oxygen is mainly characterized by peroxynitrite and not by HO( small middle dot) radicals. Quantum-chemical calculations predict that peroxynitrite formation should proceed via intermediary formation of (*)NO and O(2), probably by an electron-transfer mechanism. This prediction is supported by the fact that H(2)O(2) is formed during the decay of NO(-) in the presence of superoxide dismutase (Cu(II),Zn-SOD). Since the nitroxyl anion may be released endogenously by a variety of biomolecules, substantial amounts of peroxynitrite might be formed in vivo via NO(-) in addition to the "classical" ( small middle dot)NO + O(2)() pathway.
authors.affiliation: Institut für Physiologische Chemie, Universitätsklinikum, Hufelandstrasse 55, D-45122 Essen, Germany. michael.kirsch@uni-essen.de
authors.forename: Michael
authors.initials: M
authors.lastname: Kirsch
authors.forename: Herbert
authors.initials: H
authors.lastname: de Groot
mesh_terms: D000818:Animals; D000838:Anions; D000975:Antioxidants / Q000737:chemistry*; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D008981:Molsidomine / Q000031:analogs & derivatives* / Q000737:chemistry; D009243:NAD / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry; D009569:Nitric Oxide / Q000737:chemistry; D020030:Nitric Oxide Donors / Q000737:chemistry; D009573:Nitrites / Q000737:chemistry; D009589:Nitrogen Oxides / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000138:chemical synthesis*; D012235:Rhodamines / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000494:pharmacology
chemical_list: D000838:Anions; D000975:Antioxidants; D009566:Nitrates; D020030:Nitric Oxide Donors; D009573:Nitrites; D009589:Nitrogen Oxides; D012235:Rhodamines; D009243:NAD; C058319:dihydrorhodamine 123; D030421:Peroxynitrous Acid; C021229:oxyhyponitrite; D009569:Nitric Oxide; C002385:linsidomine; D006861:Hydrogen Peroxide; D008981:Molsidomine; D013482:Superoxide Dismutase; C039900:nitroxyl; D010100:Oxygen