In Vitro Calcium-Chelating and Platelet Anti-Aggregation Activities of Soy Protein Hydrolysate Modified by the Alcalase-Catalyzed Plastein Reaction

Soy protein hydrolysate (SPH) (1 mg/mL), generated by alcalase, had a calcium-chelating activity of 41 mg/g peptide. The alcalase-catalyzed plastein reaction of SPH was carried out in different media: ethanol–water, methanol–water and water. The effects of SPH and of resulting modified hydrolysates on calcium-chelating activities and inhibition of calcium precipitation and platelet aggregation were assessed in vitro . The optimum ethanol concentration, alcalase level and reaction temperature for the plastein reaction was 56.8% v/v, 5.26 kU/g peptide and 33.1C, respectively. The modified hydrolysates had better calcium-chelating activities and stronger inhibition of calcium precipitation and platelet aggregation than SPH. The modified hydrolysate with the highest calcium-chelating activity showed the strongest inhibitory effects on platelet aggregation and calcium precipitation. The plastein reaction enhances the in vitro calcium-chelating and platelet anti-aggregation activities of SPH. Practical Applications In this study, an alcalase-catalyzed plastein reaction carried out in three media (ethanol–water, methanol–water and water) was used to modify the in vitro calcium-chelating and platelet anti-aggregation activities of an alcalase-generated soy protein hydrolysate. The results revealed that the modified hydrolysates of higher calcium-chelating activity had stronger inhibitory effects on platelet aggregation and calcium precipitation. The results of this study provide further insight on the enzymatic synthesis of bioactive peptides of higher activity using the plastein reaction.