Effect of γ-irradiation on the molecular properties of ovalbumin and ovomucoid and protection by ascorbic acid

To elucidate the effect of gamma-irradiation on the molecular properties of ovalbumin and ovomucoid, the secondary and tertiary structure and molecular weights of the proteins were examined after irradiation at various doses. Gamma-irradiation of protein solutions caused the disruption of the ordered structure of protein molecules. Circular dichroism showed that increase of radiation decreased the ordered structure of proteins. Fluorescence spectroscopy indicated that irradiation quenched the emission intensity excited at 280 nm. SDS-PAGE indicated that radiation caused initial fragmentation of polypeptide chains and, as a result, subsequent aggregation. Ascorbic acid protected against the aggregation and degradation of proteins by scavenging oxygen radicals produced by irradiation and the effect of irradiation on protein conformation was more significant at lower concentrations of proteins.