ESR spectral change of radicals produced in L-alanine-3,3,3-d3 and L-alanine-d4. -A new pathway to produce the de-hydrogen radical and the hydrogen exchange reactions of the de-amino radical-

摘要

Radicals produced in L-alanine-3,3,3-d3 and L-alanine-d4 by X-irradiation and their spectral change were investigated using X-band ESR. Apparently, two major radicals appeared. One is the radical formed by deamination from a protonated anion and the other is produced by the loss of an alpha hydrogen. Before the appearance of the de-hydrogen radical, the precursor radical with a singlet feature was observed at 148-158 K. The signal of the precursor decreased and that of the de-hydrogen radical increased with temperature. Because the feature of the precursor radical was a singlet, it will be produced by deprotonation of the alpha hydrogen from the deprotonated cation radical observed at 77-80 K. Protonation to the amine moiety of the deprotonated radical will be a new pathway to produce the de-hydrogen radical.