Localization of G1A1a Allergenic Domain Destroyed by Thermal Processing

Glycinin is an important allergenic protein. A1a is the acidic chain of the G1 subunit in glycinin (G1A1a), and it has strong allergenicity. In this study, we used phage display technology to express the protein of G1A1a and its overlapping fragments and an indirect enzyme-linked immunosorbent assay (iELISA) to determine the antigenicity and allergenicity of the expressed protein. After three rounds of screening, it was determined that fragment A1a-2-B-I (¹⁵¹SLENQLDQMPRRFYLAGNQEQEFLKYQQEQG¹⁸¹) is the allergenic domain of G1A1a destroyed by thermal processing. In addition, three overlapping peptides were synthesized from fragments A1a-2-B-I, and a linear epitope was found in this domain through methods including dot blot and iELISA. Peptide 2 (¹⁵⁷DQMPRRFYLANGNQE¹⁷⁰) showed allergenicity, and after replacing it with alanine, it was found that amino acids D¹⁵⁷, Q¹⁵⁸, M¹⁵⁹, and Y¹⁶⁴ were the key amino acids that affected its antigenicity, while Q¹⁵⁸, M¹⁵⁹, R¹⁶², and N¹⁶⁸ affected allergenicity.