Role of amyloid type cross β-structure in the formation of soluble aggregate and gel in heat-induced ovalbumin

The heat-induced denaturation curve of ovalbumin followed by the ellipticity at 222 nm in circular dichroism spectra was consistent with that monitored by fluorescence with thioflavin T, which is an indication of amyloid fibril formation, while other proteins such as lysozyme and ovotransferrin did not fluoresce with thioflavin T during heat denaturation. The amount of soluble aggregate formed during heat denaturation was proportional to the increase in fluorescence with thioflavin T. The binding of soluble aggregates with thioflavin T was greatly suppressed in heat-denatured ovalbumin in the presence of thioflavin T. The similar inhibition effect of thioflavin T on the gel formation of heat-induced ovalbumin was observed. These results suggest that the amyloidogenic intermolecular beta-structure is involved in the formation of soluble aggregate and gel of heat-induced ovalbumin.