Acid-catalysed autoreduction of ferrylmyoglobin in aqueous solution studied by freeze quenching and ESR spectroscopy
- 1 January 1999
- journal article
- research article
- Published by Taylor & Francis in Free Radical Research
- Vol. 30 (4), 305-314
- https://doi.org/10.1080/10715769900300331
Abstract
Decay of the hypervalent muscle pigment ferrylmyoglobin, formed by activation of metmyoglobin by hydrogen peroxide, was found, when studied by a combination of ESR and UV/VIS spectroscopy in aqueous solution at physiological pH, to proceed by parallel second- and first-order kinetics. At pH below 6.5 a sharp ESR signal (g = 2.003) with an increasing intensity for decreasing pH were observed in solutions frozen in liquid nitrogen, and a broad signal (g = 2.005) was seen throughout the studied pH range also in frozen solutions. The g = 2.005 signal is suggested to arise from an intermediate formed in an intramolecular rate-determining electron-transfer in ferrylmyoglobin, whereas the g = 2.003 signal is caused by a radical formed in a proton-assisted electron-transfer initiating the specific acid-catalysed autoreduction.Keywords
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