Reduction of antigenicity of Cry j 1, a major allergen of Japanese cedar pollen, by thermal denaturation.

The soluble aggregates of Cryj 1, a major allergen of Japanese cedar pollen, were formed without any coagulates during heat treatment at acidic pH 5, as shown in HPLC and SDS―PAGE patterns. A remarkable change in the CD spectrum was observed between native and heat-denatured Cryj 1 at a linear rate of 1 °C/min from 40 to 90 °C. The negative peak of native Cryj I at 222 nm was moved to 218 nm, suggesting the transition of an α-helix to β-structure during heat denaturation. The increase in β-structure was also observed during heat denaturation by monitoring the fluorescence with ThioflavinT. These results suggest that Cryj 1 forms intermolecular cross-β-structure between denatured proteins during heating at 90 °C. The antigenicity of Cryj 1 detected by dot-blottingwas greatly diminished during heating at a linear rate of 1 °C/min from 40 to 90 °C without any coagulates. These results suggest that IgE epitopes exposed on the molecular surface of Cryj 1 was buried inside soluble aggregates through intermolecular β-structure formed by heating.