Electron Spin Resonance Studies of Mechanisms for Chemical Protection from Ionizing Radiation

Abstract

Small concentrations of the sulfur-containing chemical protectors, such as cysteine, cysteamine, AET, glutathione, and Na/sub 2/S/sub 2/O/sub 4/, in solid solution in certain proteins are found to alter completely the form of the electron spin resonance produced by ionizing radations in the proteins. For example, solutions of only 1/4 of 1% by weight of cysteine or NA/sub 2/S/sub 2/O/ sub 4/ in zein (or two molecules of solute per protein molecule) produce resonances when gamma -irradiated which are entirely different from that of pure zein when gamma -irradiated. It is believed that these sulfur protectors form complexes with the proteins they protect and thus absorb the ionization or damage that would occur in the unprotected protein. The results indicate that an electron hole or electron spin density can migrate through certain segments of polypeptide chains of proteins. (auth)