The identity and structure of free radicals in γ-irradiated amino acid derivatives

The technique of electron paramagnetic resonance spectroscopy was used to determine the identity and structure of free radicals produced at room temperature by gamma-irradiated powders of some biologically important compounds, namely, N-acetyl-L-glutamine, glycine ethyl ester hydrochloride and L-threonine. The paramagnetic species observed in these compounds were identified as H(2)NCOCH(2)(C) over dotH(2)C(NHCOCH(3))COOH, (C) over dotH(2)COOCH(2)CH(3) and CH(3)CH(OH)(C) over dotHCOOH, respectively. The g values and the hyperfine structure constants of the unpaired electron with the environmental protons and the (14)N nucleus were determined. The free radicals were stable at room temperature for more than three months. Some spectroscopic properties and suggestions concerning the possible structure of the radicals were also discussed in this study.