Glycosylation between recombinant peanut protein Ara h 1 and glucosamine could decrease the allergenicity due to the protein aggregation

Abstract

As a key peanut allergen, the immunoreactivity of Ara h 1 is significantly affected by protein structure which is found to be modified by various processing, although the molecular basis for this regulation has remained largely unknown. Here we explored the effect of glycosylation and glycation on the structure and antigenicity of recombinant peanut protein Ara h 1 (rAra h 1). The structural alterations were analyzed by SDS-PAGE and spectroscopic methods. ELISA, immunoblotting and degranulation test were performed to characterize the allergenicity change. Both temperature and saccharides type influenced the structure of allergic polymers formed during the glycation and glycosylation. rAra h 1 glycated by sucrose contained the IgE-binding capacity, for the intact linear epitopes were conserved during the cross linking. Our results show that glycosylation between rAra h 1 and glucosamine could be used as an effective method to lower the antigenicity of the allergen. Molecular modifications of free amino acid residues lead to the loss of both linear and conformational epitopes. Aggregates formed during glucosamine glycosylation increased the steric hindrance and destructed the intact epitopes, caused a decreased immunogenicity of rAra h 1.