Corn distillers solubles by two-step proteolytic hydrolysis as a new source of plant-based protein hydrolysates with ACE and DPP4 inhibition activities

Abstract

Proteins of low-value and underexplored corn distillers solubles (CDS) have not been considerably valorized. Hence, the influence of one-step enzymatic hydrolysis of proteins with alcalase (A), trypsin (T) or flavourzyme (F) and two steps with AT, TA, AF, FA, TF, or FT was assessed to release peptides with angiotensin-I converting enzyme inhibition (ACEi) and dipeptidyl peptidase4 inhibition (DPP4i). The AF hydrolysate was the best sample in terms of yield, protein content, degree of hydrolysis, ACEi (97.68 ± 1.09 %), and DPP4i (51.51 ± 0.28 %). Mass spectrometry of the most active AF hydrolysate (<3 kDa) identified new major peptides like APLA, PLFP, LFLP, LPPYL, PLYPLP, NDWHTGPL, LPPYLPS, GSPFLGQ, SWQQPIVGG. Bioinformatic analysis showed these can inhibit both ACE and DPP4. This is because peptides contain functional groups and adopt conformations significantly binding with other functional groups at enzyme active sites (p < 0.05). This establishes dual bioactivity of peptides, which may have applications in food, feed, and pharmaceutical industries.