Formation of Free Radicals in Aliphatic and Aromatic Amino Acids by Trapped Electrons: An E.S.R. Study

Summary

E.S.R. spectroscopy has been used to study the reactions of certain amino acids with the trapped electrons generated by x-irradiation of alkaline solutions and photoionization of K₄Fe(CN)₆ in alkaline solutions, both at 77°K. In the aliphatic amino acids, glycine and alanine, no radicals characteristic of the solute are induced during irradiation. However, thermal or photobleaching of the trapped electrons results in the formation of hydrogen abstraction radicals. In the presence of potassium nitrate, these radicals are not observed. In the case of aromatic amino acids, tryptophan, tyrosine and phenylalanine, hydrogen addition radicals are seen immediately after irradiation. Potassium nitrate also suppresses these radicals. They are not observed in the photoionized system.