Purification and characterization of a novel angiotensin I-converting enzyme-inhibitory peptide derived from Alaska pollack skins

Hydrolysates containing angiotensin I-converting enzyme (ACE)-inhibitory peptide were prepared from protein of Alaska pollack skins using alcalase and trypsin. The protein hydrolysate was separated by ultrafiltration, Sephadex G-25 gel filtration chromatography and reversed phase high-performance liquid chromatography (HPLC), from which a novel purified peptide was obtained. Both random coil structure and beta-sheet in the purified peptide were revealed in Fourier transform infrared spectrum. The amino sequence of the purified peptide was identified as GPLGVP, VLYPVK, VFLENVLR, and FEEF by HPLC-Q-TOF-MS (HPLC-quadrupole time-of-flight mass spectrometry). The peptide GPLGVP whose molecular weight was 538.31 Da showed the highest ACE inhibitory activity (IC50 = 105.8 mu M). The purified peptide featured a noncompetitive inhibition kinetic mechanism was shown in the Lineweaver-Burk plots and was susceptible to enzymes as indicated in the studies on stability of gastrointestinal proteases. Moreover, the peptide GPLGVP can combine ACE catalytic pocket through hydrogen bonds and other forces with high binding power as disclosed in molecular docking simulation, which provides the inhibitory effect of GPLGVP on ACE.

Automated summary

In this study, hydrolysates containing ACE-inhibitory peptides were prepared from Alaska pollack skins, with the most active peptide being GPLGVP. The peptide was characterized using various methods, showing the inhibitory effect on ACE through binding interactions revealed in molecular docking simulations.