Purification and identification of ACE-inhibiting peptides from wild pine nut peptide fractions (PNPF)

Pine nut is a substance rich in nutrients. The protein content of nut is 47.69%, which is rich in the essential amino acids required by human body, and is the source of nutritionally balanced protein. Pine nut is a good source for the preparation of bioactive peptides due to its special amino acid composition. Isolate protein was obtained from Changbai Mountain pine nut, it was hydrolyzed by alkaline protease, and the hydrolysates were separated and purified by ultrafiltration, Sephadex G-15, and RP-HPLC. The ACE inhibitor peptides sequence of YLLK (Tyr-Leu-Leu-Lys), YLVPH (Tyr-Leu-Val-Pro-His), and YRLD (Tyr-Arg-Leu-Asp) were identified from PNPF using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry (MALDI TOF/TOF MS). In the present study, in vitro cell experiment and gastrointestinal simulation of pine nut peptide fractions (PNPFs) were investigated. Results indicated that a certain concentration of PNPF (YLVPH,YRLD, and YLLK) had the inhibition of cell proliferation. However, the addition of PNPF (YLVPH,YRLD, and YLLK) can alleviate the damage of HUVEC which was added the Ang II (10(-7) mol/L). Combined with the whole gastrointestinal tract simulation environment, YLVPH peptide and YRLD peptide were not suitable for use as an ACE inhibitory peptide. YLLK peptide was very suitable for use as an ACE inhibitory peptide.