Purification and identification of ACE inhibitory peptides from Haruan (Channa striatus) myofibrillar protein hydrolysate using HPLC–ESI-TOF MS/MS

• Published in: Food chemistry 2011-12, Vol.129 (4), p.1770-1777
• Main Authors: Ghassem, Masomeh, Arihara, Keizo, Babji, Abdul Salam, Said, Mamot, Ibrahim, Saadiah
• Format: Article
• Language: English
• Subjects: ACE-inhibitory activity; Biological and medical sciences; Channa striatus; Electrospray ionisation; Food industries; Fundamental and applied biological sciences. Psychology; Mass spectrometry; Quadropole-time of flight; Thermolysin hydrolysate
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2011.06.051

► Haruan (Channa striatus) is an important freshwater fish cultured in Malaysia. ► Aim of this study was to isolate ACE inhibitors from Haruan protein hydrolysate. ► Thermolysin hydrolysate was purified and peptide sequence was identified by LC–MS-TOF. ► Two sequences identified as VPAAPPK (IC50=0.45μM) and NGTWFEPP (IC50=0.63μM). ► It is suggested that Haruan may be used as functional food to prevent hypertension. Haruan myofibrillar protein was hydrolysed with proteinase K and thermolysin to isolate Angiotensin converting enzyme (ACE) inhibitory peptides. The thermolysin hydrolysate of myofibrillar protein with the highest ACE inhibition activity (IC50=0.033mg/ml) was fractionated by ultrafiltration and size exclusion chromatography to three fractions. Fraction F2 with higher ACE inhibitory activity was separated into five fractions (A–E) using reversed-phased high performance liquid chromatography (RP-HPLC). Fraction C showed 81% inhibition activity and was subjected to HPLC coupled to electrospray ionisation-time-of-flight mass spectrometry (ESI-TOF MS/MS). Two peptide sequences for the most abundant fragments were identified as VPAAPPK (IC50=0.45μM) at 791.155m/z and NGTWFEPP (IC50=0.63μM) at 1085.841m/z. The presence of two proline residues at the C-terminal sequence is responsible for the high ACE inhibitory activity of these peptides. The results suggest that Haruan meat protein hydrolysate is a potent ACE inhibitor and may be used to decrease blood pressure.