Tryptophan-14 Is the Preferred Site of DBNBS Spin Trapping in the Self-Peroxidation Reaction of Sperm Whale Metmyoglobin with a Single Equivalent of Hydrogen Peroxide
| Autor: | Richard A. Tschirret-Guth, Michael R. Gunther, Olivier M. Lardinois, Paul R. Ortiz de Montellano |
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| Rok vydání: | 2003 |
| Předmět: |
Free Radicals
Pronase Toxicology Photochemistry law.invention Adduct chemistry.chemical_compound Nuclear magnetic resonance Species Specificity law Animals Horses Hydrogen peroxide Electron paramagnetic resonance Spin trapping Chemistry Benzenesulfonates Electron Spin Resonance Spectroscopy Tryptophan Whales Hydrogen Peroxide General Medicine Oxidants Metmyoglobin Myoglobin Tyrosine Spin Trapping Nitroso Compounds |
| Zdroj: | Chemical Research in Toxicology. 16:652-660 |
| ISSN: | 1520-5010 0893-228X |
| DOI: | 10.1021/tx0256580 |
| Popis: | The 3,5-dibromo-4-nitrosobenzenesulfonate (DBNBS)-metmyoglobin adduct formed following the horse metmyoglobin-H 2 O 2 reaction has been assigned to both a tyrosyl and a tryptophanyl residue radical. At low H 2 O 2 , hyperfine coupling to a 1 3 C atom in sperm whale metmyoglobin labeled at the tryptophan residues with 1 3 C allowed the unequivocal assignment of the primary adduct to a tryptophanyl radical. Trapping at Trp-14 of sperm whale myoglobin was indicated by greatly decreased electron paramagnetic resonance (EPR) spectral intensity of the DBNBS adducts of the Trp-14-Phe recombinant proteins. Complex EPR spectra with partially resolved hyperfine splittings from several atoms were obtained by pronase treatment of the DBNBS/ .W14F metmyoglobin adducts. The EPR spectra of authentic DBNBS/Tyr adducts were incubation time-dependent; the late time spectra resembled the spectra of pronase-treated DBNBS/W14F sperm whale myoglobin adducts, suggesting formation of an unstable tyrosyl radical adduct in the latter proteins. When the H 2 O 2 :metmyoglobin ratio was increased to 5:1, the EPR spectrum after pronase treatment supported trapping of a tyrosyl radical, although similar decreases in tryptophan content were detected at H 2 O 2 :metmyoglobin ratios of 1:1 and 5:1. |
| Databáze: | OpenAIRE |
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