Characteristics of molecular composition and its anti-nutrition of β-conglycinin during flavorzyme proteolysis

β-conglycinin is one of the main protein components in soybean that cause human allergy and it is difficult to eliminate the antigenicity of β-conglycinin using common enzymolysis, the reason of which is not clear. We analyzed the molecular composition, antigenic activity, and sequential epitopes of the hydrolysates of this protein after digestion with flavorzyme using SDS-PAGE, ELISA, MALDI-TOF-MS, and protein and antigen database retrieval. Results showed that α′-and α-subunits of β-conglycinin were nearly completely degraded 10 min after enzymolysis and that the protein retained 92.7% antigenic activity. Newly produced peptides, including those of 35, 23, 17, and 11 ku, were formed. These peptides and the 49 ku β-subunit were not degraded completely even after 150 min of enzymolysis, thus indicating evident resistance to enzymatic hydrolysis. Moreover, the antigenic activity of the protein maintained at 43.5%. Epitope analysis revealed that the newly formed 49, 35, 23, 17, and 11 ku peptides contain twenty seven antigen epitopes, including two from the α-subunit, ten from the α′-subunit, and fifteen from the β-subunit of β-conglycinin. These findings suggest the relationship between existence of anti-enzymolysis fragments and their epitopes and incomplete elimination of antigenicity of β-conglycinin.