Radiation-induced protein fragmentation and inactivation in liquid and solid aqueous solutions. Role of OH and electrons

Abstract Irradiation of proteins in diluted liquid aqueous solutions produces cleavages and polymerizations of the peptidic chains. In frozen solutions, fragmentation is observed but polymerization products are absent. Loss of activity occurs in both cases. In the solid state, yields of fragmentation do not vary with the quantity of water. The use of scavengers indicates that hydroxyl radical does not contribute significantly to fragmentation and to inactivation in the solid state. Electrons within the water molecules closely associated with the protein are involved in the processes leading to protein fragmentation.