Purification and molecular docking of angiotensin converting enzyme-inhibitory peptides derived from corn gluten meal hydrolysate and from in silico gastrointestinal digestion

Corn gluten meal (CGM) was hydrolyzed by Alcalase with the degree of hydrolysis (DH) and protein recovery of 28.7 % and 67.7 %, respectively. Ultrafiltration revealed that the 3-10 kDa fraction (IC50 = 15.98 mu g/mL) involved potent ACE inhibitory peptides. The peptides in the fraction were further separated by size exclusion chromatography and reverse-phase chromatography. The novel peptide DLLGCS was identified to be the most active ACE inhibitor (IC50 = 39.0 mu M). The in silico digested peptide CS was approximately 4.5 times higher than its parent counterpart (IC50 = 8.5 mu M). Peptides CS and DLLGCS showed an uncompetitive inhibitor characteristic with Ki values of 12.52 and 11.40 mu M, respectively. Based on molecular docking, both peptides interacted with the nonactive site of ACE, primarily via hydrogen bonds at Arg522, Asp121, Glu123 and Lys118 residues for DLLCGS and Glu162, Ser147 and Glu349 residues for CS. Therefore, peptides originated from CGM hydrolysates could exhibit a higher degree of inhibition against ACE enzyme upon gastrointestinal digestion, which is likely to be a potential source of bioactive peptides with ACE inhibitory activity.