In agreement with previous reports (Gasyna, Z. FEBS Lett. 1979, 106, 213-218 and Leibl, W.; Nitschke, W.; Huettermann, J. Biochim. Biophys. Acta 1986, 870, 20-30) radiolytically reduced samples of oxygenated myoglobin at cryogenic temperatures have been shown by optical absorption and EPR studies to produce directly the peroxo-bound myoglobin at 77 K. Annealing to temperatures near 185 K induces proton transfer, resulting in the formation of the hydroperoxo heme derivative. Resonance Raman studies of the annealed samples has permitted, for the first time, the direct observation of the key ν(Fe-O) stretching mode of the physiologically important Fe-OOH fragment of this ubiquitous intermediate. The assignment of this mode to a feature appearing at 617 cm-1 is strongly supported by documentation of a 25 cm -1 shift to lower energy upon substitution with 18O 2 and by a 5 cm-1 shift to lower energy for samples prepared in solutions of deuterated solvent.
ASJC Scopus subject areas
- Colloid and Surface Chemistry