Identification and Validation of Soy Peptides with In‐vitro Hemagglutination Activity

Abstract We previously demonstrated that different enzyme hydrolysates of soybean agglutinin (SBA), β‐conglycinin and glycinin‐rich fractions had in‐vitro hemagglutination activities. In the present study, the three proteins were subjected to trypsin hydrolysis, and N‐acetyl‐d‐galactosamine (GalNAc)‐agarose beads were used to isolate the active peptides. Matrix Assisted Laser Desorption/Ionization Time‐of‐Flight (MALDI−TOF) Mass Spectrometry (MS) was used to determine the mass of the peptides and the molecular weights were compared to the peptide profiles given by theoretical cleavage of the proteins, so that the peptide sequence could be identified. Two peptides from SBA, 24 peptides from β‐conglycinin and 16 peptides from glycinin were identified from the active peptide extracts. The two SBA peptides, three peptides from β‐conglycinin having strong MS signal intensity and three peptides from glycinin with strong MS intensity were synthesized and their activities were assessed by using the in‐vitro hemagglutination assay. These peptides were proven to have hemagglutination activity, whereas a synthesized control peptide from SBA did not. These results validated our previous observation of various soy protein fractions having hemagglutination activities.