Determination of Molecular Weight of Soluble Ovalbumin Aggregates during Heat Denaturation Using Low Angle Laser Light Scattering Technique

Abstract

The apparent molecular weights of soluble ovalbumin aggregates occurring under various heating conditions were determined by using the low angle laser light scattering technique in combination with high performance liquid chromatography. The soluble ovalbumin aggregates were rapidly formed near the melting point (76°C) for thermal denaturation. The apparent molecular weight of the soluble ovalbumin aggregates increased with the heating temperature from 4,000,000 at 76°C to 35,000,000 at 100°C. It also increased in proportion to the protein concentration, ionic strength and standing time. In the presence of sodium dodecyl sulfate, the soluble ovalbumin aggregates dissociated into lower molecular weight fractions, mainly monomeric and oligomeric. On the other hand, the molecular weight of the soluble ovalbumin aggregates did not change in the presence of mercaptoethanol or N-ethylmaleimide. The soluble ovalbumin aggregates were formed in proportion to an increase in the surface hydrophobicity of heat-denatured ovalbumins. From these results, it was suggested that the soluble ovalbumin aggregates were formed mainly by hydrophobic interaction.