RADIATION-INDUCED CROSS-LINKING AND SCISSORING OF PROTEINS IN EGG-WHITE

Two kinds of radiation-induced protein damages, cross-linking and scis soring, were studied using a thin fraction of avian egg white. It was found that at a dose of 10 kGy in N2O saturated samples only one third of the affected protein molecules underwent aggregation, while, contr ary to the results obtained with diluted protein solutions, the rest t ook part in the fragmentation reaction. The fragments obtained had a u niform molecular weight distribution. The overall G-value was found to be 0.25. In air saturated samples the scissoring dominated ten times over cross-linking with the fragments of discrete and well resolved mo lecular weights. The overall G-value was equal to 0.3. Both G-values a re three times smaller than the corresponding values obtained in the e xperiments with denatured and purified proteins. The egg white radiati on stability was found to be, at least in part, due to the presence of glucose which, in turn, acts as an antioxidant. Other relevant factor s which may affect the radiation chemistry of the egg white protein co mposite are also discussed.