Isolation and purification of ACE inhibitory peptidic fractions from freshwater fish muscle protein thermolysin hydrolysate

摘要

"Haruan" (Channa striatus) is a freshwater fish popular among post-operative patients to induce wound healing in Malaysia. Hypertension is considered a risk factor for developing cardiovascular diseases and ACE is involved in increasing blood pressure. This study was conducted to evaluate the ACE inhibitory activity of haruan muscle protein hydrolysate. Myofibrillar protein was hydrolysed with thermolysin at 37°C for 2 h. The thermolysin catalysed hydrolysate with degree of hydrolysis of 89% was fractionated by ultrafiltration membranes size 10 and 3 KD molecular weight cut-off (MWCO), respectively. Peptides with MWCO < 3 KD exhibited high ACE inhibitory activity (IC_(50) = 0.033 mg/mL) and were separated into three fractions with gel chromatography on polyacrylamide Bio-Gel P-2 column. Fraction 2 with the ACE inhibitory activity of 67.23% was further separated into five (A-E) potent fractions with reversed-phased high performance liquid chromatography (RP-HPLC), which Fraction C with the lowest IC_(50) value of 10.32 μg/mL was lyophilized and characterized with HPLC mass spectrometry-Time Of Flight (LC-MS-TOF). Two peptides with the sequences of VPAAPPK and NGTWFEPP with IC_(50) value of 0.45 and 0.63 uM were identified for the most active fraction C, respectively. The high ACE inhibitory activity suggests that haruan muscle protein thermolysin hydrolysate could be used as functional ingredients for blood pressure reduction.