ACE inhibitory peptides derived from sarcoplasmic enzymatic hydrolysate of freshwater fish haruan

摘要

Hypertension is one of the major risk factor for development of cardiovascular diseases. Among the process related to hypertension, ACE plays a crucial role in the regulation of blood pressure. In this study, sarcoplasmic protein hydrolysates of freshwater fish haruan (Channa striatus), obtained by treatment with proteinase K, thermolysin and the mixture of enzymes, were analyzed for their ACE inhibitory activities. Hydrolysate generated with proteinase K, with degree of hydrolysis of 89% and molecular weight cutoff less than 3 KD, displayed the lowest IC_(50) value of 0.038 mg/mL. This hydrolysate was then fractionated by size exclusion chromatography on polyacrylamide Bio-Gel P-2 column into four fractions (P1-P4). P4 was found to display the highest ACE inhibitory activity (75.23%) and then fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC) into seven fractions (A-G). The amino acid sequence of sub-fraction F with the strongest ACE inhibitory activity, (81%) was determined by ESI-MS/MS as YSMFPP with the IC_(50) value 1.8 uM. The ACE inhibitory activity of purified peptide did not change after in vitro digestion with gastrointestinal proteases. The results of this study presented a new ACE inhibitory peptide formed from sarcoplasmic protein hydrolysate of Haruan fish meat which could be used as health enhancing ingredient in the formulation of functional foods in order to prevent hypertension.