title: Room temperature Q-band electron magnetic resonance study of radicals in X-ray-irradiated l-threonine single crystals.
abstract: In the past, decennia radiation-induced radicals were successfully identified by electron magnetic resonance (EMR) in several solid-state amino acids and sugars. The authors present a room temperature (RT) EMR study of the stable radicals produced by X-ray-irradiation in the amino acid l-threonine (CH₃CH(OH)CH(NH₃ (+))COO(-)). Its chemical structure is similar to that of the well-known dosimetric material l-alanine (CH₃CH(NH₃(+))COO(-)), and radiation defects in l-threonine may straightforwardly be compared with the extensively studied l-alanine radicals. The hyperfine coupling tensors of three different radicals were determined at RT using electron nuclear double resonance. These results indicate that the two most abundant radicals share the same basic structure CH₃(•)C(OH)CH(NH₃(+))COO(-), obtained by H-abstraction, but are stabilised in slightly different conformations. The third radical is most probably obtained by deamination (CH₃CH(OH)(•)CHCOO(-)), similar in structure to the stable alanine radical.
authors.affiliation: Department of Solid State Sciences, Ghent University, Krijgslaan 281 - S1, Gent 9000, Belgium.
authors.forename: Gauthier
authors.initials: G
authors.lastname: Vanhaelewyn
authors.affiliation: Department of Solid State Sciences, Ghent University, Krijgslaan 281 - S1, Gent 9000, Belgium.
authors.forename: Henk
authors.initials: H
authors.lastname: Vrielinck
authors.affiliation: Department of Solid State Sciences, Ghent University, Krijgslaan 281 - S1, Gent 9000, Belgium freddy.callens@ugent.be.
authors.forename: Freddy
authors.initials: F
authors.lastname: Callens
mesh_terms: D003460:Crystallization; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D005609:Free Radicals / Q000737:chemistry / Q000528:radiation effects*; D006801:Humans; D011874:Radiometry / Q000379:methods*; D013696:Temperature; D013912:Threonine / Q000737:chemistry / Q000528:radiation effects*; D014965:X-Rays
chemical_list: D005609:Free Radicals; D013912:Threonine