Site-specific spin trapping of tyrosine radicals in the oxidation of metmyoglobin by hydrogen peroxide
- 15 March 1998
- journal article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 330 (3), 1293-1299
- https://doi.org/10.1042/bj3301293
Abstract
The reaction between metmyoglobin and hydrogen peroxide produces both a ferryl-oxo heme and a globin-centred radical(s) from the two oxidizing equivalents of the hydrogen peroxide. Evidence has been presented for localization of the globin-centred radical on one tryptophan residue and tyrosines 103 and 151. When the spin-trapping agent 5,5-dimethyl-1-pyrroline N-oxide (DMPO) is included in the reaction mixture, a radical adduct has been detected, but the residue at which that adduct is formed has not been determined. Replacement of either tryptophans 7 and 14 or tyrosines 146 and 151 with phenylalanine has no effect on the formation of DMPO adduct in the reaction with hydrogen peroxide. When tyrosine 103 is replaced with phenylalanine, however, only DMPOX, a product of the oxidation of the spin-trap, is detected. Tyrosine-103 is, therefore, the site of radical adduct formation with DMPO. The spin trap 2-methyl-2-nitrosopropane (MNP), however, forms radical adducts with any recombinant sperm whale metmyoglobin that contains either tyrosine 103 or 151. Detailed spectral analysis of the DMPO and MNP radical adducts of isotopically substituted tyrosine radical yield complete structural determinations. The multiple sites of trapping support a model in which the unpaired electron density is spread over a number of residues in the population of metmyoglobin molecules, at least some of which are in equilibrium with each other.Keywords
This publication has 29 references indexed in Scilit:
- ESR Spin-trapping of a Protein-derived Tyrosyl Radical from the Reaction of Cytochrome with Hydrogen PeroxideJournal of Biological Chemistry, 1996
- Self-peroxidation of Metmyoglobin Results in Formation of an Oxygen-reactive Tryptophan-centered RadicalJournal of Biological Chemistry, 1995
- The Role of H2O2-Generated Myoglobin Radical in Crosslinking of MyosinFree Radical Research, 1995
- Decay Studies of Dmpo-Spin Adducts of Free Radicals Produced by Reactions of Metmyoglobin and Methemoglobin with Hydrogen PeroxideFree Radical Research, 1995
- Oxidation of spin trap 5,5-dimethyl-1-pyrroline-1-oxide in an electron paramagnetic resonance study of the reaction of methemoglobin with hydrogen peroxideFree Radical Biology & Medicine, 1994
- Identification of initiating agents in myoglobin-induced lipid peroxidationBiochemical and Biophysical Research Communications, 1991
- Identification of a globin free radical in equine myoglobin treated with peroxidesBiochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 1991
- Long range electron transfer between tyrosine and tryptophan in hen egg-white lysozymeBiochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 1991
- Pulse radiolytic measurement of redox potentials: the tyrosine and tryptophan radicalsBiochemistry, 1989
- Oxidation of Dimethylsulphoxide to Formaldehyde by Oxyhaemoglobin and Oxyleghaemoglobin in the Presence of Hydrogen Peroxide is Not Mediated by “Free” Hydroxyl RadicalsFree Radical Research Communications, 1989