Production of the Angiotensin-I-Converting Enzyme (ACE)-Inhibitory Peptide from Hydrolysates of Jellyfish (Rhopilema esculentum) Collagen

Collagen extracted from jellyfish (Rhopilema esculentum) was hydrolyzed with alcalase to prepare the ACE-inhibitory peptide. The optimal hydrolyzing conditions were determined using response surface methodology. The results showed that the optimal conditions were temperature of 52.7 °C, pH of 8.63 and enzyme-to-substrate ratio (E/S) of 3.46%, and the ACE-inhibitory activity of the obtained hydrolysates could reach 81.7%. Jellyfish collagen peptide, UF3-B2, was purified from the hydrolysates using ultrafiltration, ion-exchange chromatography and gel filtration. The IC50 value of UF3-B2 was 43 μg/ml, and the yield accounted for 6.25% of the hydrolysates. The molecular weight distribution of UF3-B2 was from 200 to 600 Da. Amino acid analyses showed that UF3-B2 was rich in Gly, Pro, Glu, Ala, and Asp.