Abstract:

The ACE inhibitory peptides derived from casein hydrolyzed with alkaline protease from Bacillus subtilis at 55 ℃ for 6 h exhibited an IC50 of 38.6μg/mL. To enhance their activity, they were modified via the plastein reaction catalyzed by the enzyme. Moreover, response surface methodology was employed to investigate the optimal values of plastein reaction parameters including enzyme dosage and reaction temperature and time. Results showed that after the optimal reaction for 6 h at 42.7 ℃ and an enzyme dosage of 7.7 kU/g protein, the content of free amino groups in the peptides were decreased by up to 179.72 μmol/g protein. The optimized plastein reaction resulted in an obvious enhancement of casein-derived ACE inhibitory peptides, which was related to the reaction degree and the IC50 of the modified ACE inhibitory peptides was reduced to 0.5μg/mL.

Key words: casein, ACE inhibitory peptides, preparation method, plastein reaction