Reduction of Antigenicity of Cry j 1, a Major Allergen of Japanese Cedar Pollen, by Thermal Denaturation

Abstract

The soluble aggregates of Cry j 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 Cry j 1 at a linear rate of 1 degrees C/min from 40 to 90 degrees C. The negative peak of native Cry j 1 at 222 nm was moved to 218 nm, suggesting the transition of an alpha-helix to beta-structure during heat denaturation. The increase in beta-structure was also observed during heat denaturation by monitoring the fluorescence with Thioflavin T. These results suggest that Cry j 1 forms intermolecular cross-beta-structure between denatured proteins during heating at 90 degrees C. The antigenicity of Cry j 1 detected by dot-blotting was greatly diminished during heating at a linear rate of 1 degrees C/min from 40 to 90 degrees C without any coagulates. These results suggest that IgE epitopes exposed on the molecular surface of Cry j 1 was buried inside soluble aggregates through intermolecular beta-structure formed by heating.