EFFECTS OF A LIMITED PROTEOLYSIS OF OVALBUMIN ON INTERFACIAL ADSORPTIVITY STUDIED BY P-31 NUCLEAR-MAGNETIC-RESONANCE

Effects of a limited proteolysis of ovalbumin on the emulsifying property were investigated with P-31 NMR spectra in correlation with the interfacial adsorptivity of the protein. The interfacial adsorptivity was evaluated by the droplet size distribution. The interfacial adsorptivity of p-ovalbumin, which was formed by cleaving the N-terminal residues (1-22) of ovalbumin, were markedly decreased, but those of plakalbumin, which was formed by cleaving the C-terminal residues (346-385) of ovalbumin, were increased. The line widths of the phosphorus signals of plakalbumin were much broadened by emulsification and those of p-ovalbumin were scarcely changed by emulsification compared to those of ovalbumin. The dynamic states of two phosphoserine moieties of ovalbumin in emulsions were elucidated by their susceptibility to acid phosphatase digestion. The line widths of P-31 NMR spectra were well correlated with the interfacial adsorptivity of ovalbumin.