Protein flexibility and functional properties of heat-denatured ovalbumin and lysozyme.

Abstract

The flexibilities of ovalbumin and lysozyme, detected by the protease-probe method, were monitored during heat-denaturation. The flexibilities of these proteins increased in the heating temperature region where the structural changes were too small to detect by other optical methods, such as surface hydrophobicity measurement. To evaluate the relationship between the structural and functional properties (foaming and emulsifying properties), the thermal denaturation curves for the flexibility and surface hydrophobicity were compared with those for the foaming power and emulsifying activity of ovalbumin and lysozyme. The thermal transition points of the foaming power closely corresponded to those of the flexibility of ovalbumin and lysozyme. On the other hand, the thermal transition points of the emulsifying activity corresponded to those of the surface hydrophobicity of ovalbumin and lysozyme. Thus, it was suggested that the flexibility of proteins may be a main governing factor for the foaming property and that the surface hydrophobicity of proteins may be a main governing factor for the emulsifying property.