Electron spin resonance spectra of free radicals formed in the reaction of metmyoglobins with ethylhydroperoxide.
Free radicals of myoglobins were measured at room temperature with an ESR spectrometer equipped with a flow apparatus. When horse heart MetMb was mixed with an equimolar amount of ethyl hydroperoxide (EtOOH), a well resolved ESR spectrum with 6 lines and a shoulder was observed. It reached a maximum in a few seconds and decayed with a half-life of about 10 s when the final concentrations of MetMb and EtOOH were 200 microM. This decay rate was the same at a MetMb concentration of 50 microM. The maximum molar radical concentration amounted to about half of the total myoglobin. In the case of sperm whale myoglobin, a similar 6-line spectrum reached a maximum in 1 s and decayed with a half-life of a few seconds. In this case, however, a small and poorly resolved doublet spectrum remained, the half-life of which was about 8 min. An effect of O2 on the signal decay was evident for horse heart myoglobin, but not for sperm whale myoglobin.
D000818:Animals; D004355:Drug Stability; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D006420:Hemeproteins / Q000032:analysis*; D006736:Horses; D008786:Metmyoglobin / Q000032:analysis*; D009206:Myocardium / Q000032:analysis; D010545:Peroxides; D014907:Whales
D005609:Free Radicals; D006420:Hemeproteins; D010545:Peroxides; C025577:ethyl hydroperoxide; D008786:Metmyoglobin