Nitric Oxide Interaction with Lactoferrin and Its Production by Macrophage Cells Studied by EPR and Spin Trapping
ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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The production of nitrate N03- and nitrite N02- from macrophage-derived NO- was studied using EPR and spin trapping. The formation of NO3- was determined via EPR in reactions involving the iron-binding protein, lactoferrin errin. The formation of NO2- was determined via EPRspin trapping in the reaction between NO2- and H2O2. Dissolved nitric oxide NO- was reacted with lactoferrin yielding an EPR spectrum 77 K different from the normal EPR spectrum obtained for lactoferrin, suggesting that NO- interacts with the ferric ions bound to lactoferrin forming a ferric-nitrosyl type complex. The EPR spectrum 77 K of this ferric-nitrosyl type complex was also observed in the supernatant fluid of macrophage cell suspensions following their stimulation with lipopolysaccharide LPS. During LPS stimulation of macrophages, these cells generate NO- which in turn produces NO3- and NO2- . The ferric-nitrosyl type complex is formed in a reaction mixture containing apolactoferrin and bicarbonate following the reaction of Fe2 with NO3- and NO-. Furthermore, in an acidic medium, NO2- reacts with H2O2 forming peroxynitrous acid HOONO which rapidly decomposes into hydroxyl radicals OH and the nitrogen dioxide NO2- radical.
- Inorganic Chemistry
- Atomic and Molecular Physics and Spectroscopy