Screening and Identification of Angiotensin-I-Converting Enzyme Inhibitory Peptides from Perilla Frutescens Seed Proteins Hydrolysate
Hypertension is considered a chronic disease and now becomes one of the most common civilized diseases. In order to improve the condition of hypertension, some chemically synthesized antihypertensive drugs have been developed, but usually accompanied by some side effects. In general, active peptides derived from natural edible protein sources are regarded as milder and safer alternatives. In this study, Perilla frutescens seed proteins were extracted, hydrolyzed using the rmolysin, and the resulting hydrolysate was filtered with an ultra filtration membrane (3kDa cut-off) to give a mixture of small peptides. The so-called bioassay-guided fractionation of the peptide mixture was performed on high-performance liquid chromatography (HPLC), and the activity of each fraction was evaluated using in vitro angiotensin-I-converting enzyme inhibitory (ACEI) assay. Two peptides (TY4 and LY4) in the most active fraction were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with de novo sequencing. The sequences of identified peptides were further confirmed using the corresponding synthetic peptides. The IC50 values of TY4 and LY4 were determined as low as 22.66±1.18 and 21.28±1.382µM, respectively. The inhibition kinetics indicated that both TY4 and LY4 were characterized as competitive inhibitors against ACE according to the result of the Line weaver-Burk plot. Furthermore, the molecular docking of the identified peptide towards ACE was also carried out, and the simulated result is consistent with that determined by the inhibition kinetics, in which the active peptidescan interact with key residues in the active site of ACE.
Keywords - Angiotensin-I-Converting Enzyme (ACE), Perilla Frutescens Seed, Hypertension, Active Peptide