Electron spin resonance spectrum of Tyr-151 free radical formed in reactions of sperm whale metmyoglobin with ethyl hydroperoxide and potassium irridate. 1989

H Miki, and K Harada, and I Yamazaki, and M Tamura, and H Watanabe
Analytical Chemistry Laboratory II, Faculty of Engineering, Hokkaido University, Sapporo, Japan.

A five-line ESR spectrum was observed at room temperature in reactions of sperm whale metmyoglobin with ethyl hydroperoxide (EtOOH) at pH 9.5 and with potassium irridate at pH's 7.0 and 9.5. A spectrum with the same g value and hyperfine splitting constant appeared in a reaction of sperm whale apomyoglobin with potassium irridate and was assigned to a tyrosyl radical on the basis of optical spectrum data obtained under the same reaction conditions. It was concluded that this radical arose from Tyr-151 for the following reasons. (i) This ESR spectrum could not be observed in the reaction of horse heart metmyoglobin, which lacks Tyr-151. (ii) Sperm whale metmyoglobin no longer gave this spectrum when treated with tetranitromethane (TNM) under conditions in which approximately one tyrosine is lost in sperm whale metmyoglobin but none is lost in horse heart metmyoglobin. (iii) A complex ESR spectrum observed in the reaction of sperm whale metmyoglobin with EtOOH at neutral pH was found to be a mixture of this five-line spectrum and one arising from an unidentified free radical formed in the reaction of horse heart metmyoglobin with EtOOH. The TNM-treated sperm whale metmyoglobin gave the same ESR spectrum as that observed in the reaction of horse heart metmyoglobin with EtOOH.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008786 Metmyoglobin Myoglobin which is in the oxidized ferric or hemin form. The oxidation causes a change in color from red to brown. Ferrimyoglobin
D010084 Oxidation-Reduction A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471). Redox,Oxidation Reduction
D010545 Peroxides A group of compounds that contain a bivalent O-O group, i.e., the oxygen atoms are univalent. They can either be inorganic or organic in nature. Such compounds release atomic (nascent) oxygen readily. Thus they are strong oxidizing agents and fire hazards when in contact with combustible materials, especially under high-temperature conditions. The chief industrial uses of peroxides are as oxidizing agents, bleaching agents, and initiators of polymerization. (From Hawley's Condensed Chemical Dictionary, 11th ed) Peroxide
D011188 Potassium An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D011487 Protein Conformation The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain). Conformation, Protein,Conformations, Protein,Protein Conformations
D004578 Electron Spin Resonance Spectroscopy A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING. ENDOR,Electron Nuclear Double Resonance,Electron Paramagnetic Resonance,Paramagnetic Resonance,Electron Spin Resonance,Paramagnetic Resonance, Electron,Resonance, Electron Paramagnetic,Resonance, Electron Spin,Resonance, Paramagnetic
D005609 Free Radicals Highly reactive molecules with an unsatisfied electron valence pair. Free radicals are produced in both normal and pathological processes. Free radicals include reactive oxygen and nitrogen species (RONS). They are proven or suspected agents of tissue damage in a wide variety of circumstances including radiation, damage from environment chemicals, and aging. Natural and pharmacological prevention of free radical damage is being actively investigated. Free Radical
D006420 Hemeproteins Proteins that contain an iron-porphyrin, or heme, prosthetic group resembling that of hemoglobin. (From Lehninger, Principles of Biochemistry, 1982, p480) Hemeprotein,Heme Protein,Heme Proteins,Protein, Heme,Proteins, Heme
D006863 Hydrogen-Ion Concentration The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations

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