In silico analysis and molecular docking study of angiotensin I-converting enzyme inhibitory peptides from smooth-hound viscera protein hydrolysates fractionated by ultrafiltration.

Smooth-hound viscera hydrolysates (SHVHs) were prepared by treatment with Neutrase (SHVH-N) and Purafect (SHVH-P). Hydrolysates were then separated according to their molecular weight, using the ultra-filtration membrane system, into 5 fractions (≥50, 50-5, 5-3, 3-1 and ≤1kDa). Fractions showed different amino acid compositions and angiotensin I-converting enzyme (ACE) inhibitory potentials. The SHVH-P-FV (≤1kDa) and SHVH-N-FIV (3-1kDa) fractions showed the best ACE-inhibitory activities with IC values of 53.31 and 75.05µg/ml, respectively. According to their high ACE-inhibitory potential, FIV and FV were fractionated by RP-HPLC and then analyzed by LC-MS/MS to identify peptide sequences. A systematic peptidomic study resulted in the identification of numerous novel sequences. Furthermore, in silico data, based on the molecular docking simulation, showed that GPAGPRGPAG, AVVPPSDKM, TTMYPGIA, and VKPLPQSG could bind ACE active site with low interaction scores. Indeed, they share hydrogen bonds and Van der Waals and electrostatic interactions with ACE catalytic pockets.