Interaction of human myeloperoxidase with nitrite.
EPR (electron paramagnetic resonance) and optical spectroscopy show that human neutrophil myeloperoxidase is converted from ferric high-spin to low-spin by the addition of nitrite. The Soret peak shifts from 429 to 447 nm and new peaks appear in the visible region at 573 and 627 nm; the EPR g-values change from 6.84, 5.02, 1.95 to 2.55, 2.31, 1.82. Small differences are seen in the EPR (but, not optical) spectra of myeloperoxidase isoenzyme I compared to isoenzymes II and III. The reaction with nitrite is detectable by EPR in intact neutrophils and is thus a possible in vivo monitor of NO/nitrite production by these cells.
Cooper
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CE
Metals in Biology and Medicine Centre, King's College London, UK.
Odell
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D002712:Chlorides / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D005290:Ferric Compounds / Q000378:metabolism; D006801:Humans; D009504:Neutrophils / Q000201:enzymology; D009573:Nitrites / Q000378:metabolism*; D009195:Peroxidase / Q000378:metabolism*; D013053:Spectrophotometry
D002712:Chlorides; D005290:Ferric Compounds; D009573:Nitrites; D009195:Peroxidase