The Migration of Radiation Damage in Reduced Glutathione

Abstract

The migration of radiation induced unpaired spins in reduced glutathione has been followed by qualitative and quantitative electron-spin-resonance (EPR) measurements. Polycrystalline glutathione was irradiated with 220 kvX-rays and kept in vacuum at room temperature. Ten minutes after exposure the spectrum resembled that of an equimolar mechanical mixture of the three constitutent amino acids. In the course of days the spectrum changed to become finally almost identical with that of irradiated cysteine. The spectrum of the mechanical mixture was shown to be a simple sum of those of the constituent amino acids in which the majority of EPR centres reside in the glutamic acid and glycine. The data indicate that in irradiated glutathione EPR centres are initially induced in all three amino acid residues. Subsequently, the EPR centres are slowly transferred to the cysteine part. This transfer may possibly involve an interaction between radiation-induced molecular fragments and intact neighbouring glutathione molecules.