Abstract
Hyperfine structure due to 17O has been measured in irradiated zein and edestin after exposure to gaseous oxygen with 17O concentrated to 24%. The observations prove that the free radicals produced by ionizing irradiation under vacuum at 300 K are converted by the oxygen to protein-peroxide free radicals X—O(1)—O(2), with the unpaired electron density in a π-type orbital predominantly on the peroxide group. From the observed couplings, the 2pπ spin densities on zein-peroxide are found to be 0.29 and 0.45 for O(1) and O(2), respectively; those on edestin-peroxide are 0.26 and 0.48 for O(1) and O(2), respectively.
Keywords: oxygenated free radicals, electron spin resonance spectra, 17O hyperfine structure
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Selected References
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