Changes in biochemical properties of ovomucoid by radiation

Radiation effects on biochemical properties of ovomucoid, a protease inhibitor which is a typical allergenic protein of egg, were investigated. Trypsin inhibiting activity of ovomucoid decreased exponentially and the inactivation was larger in N2 than in O2. The antigenicity of ovomucoid measured by ELISA was decreased exponentially and the inactivation curves were almost the same as that of trypsin inhibiting activity. These results show that the oxygen protects the inactivation and destruction of antigenicity of ovomucoid while it enhances the reaction with ovalbumin. The effect of radiolytically generated radical anions; a pronounced protective action of (CNS)2- and a slight accelerate action of Br2- were the same both on decrease in trypsin inhibiting activity and antigenicity. SDA-PAGE showed that the change in protein structure was also protected by (CNS)2-. These results suggest that the changes by radiation were not mainly due to the destruction of essential amino acid residues but to the conformational change. (Author)