Isolation and Identification of Antioxidant Peptides from Wheat Germ Protein by Pepsin Enzyme

  In recent years, there has been a growing interest to identify bioactive peptides from plant sources. Enzymatic hydrolysis of proteins is the most common method to produce bioactive peptides. Wheat germ is one of the most important by-products from flour processing industry that it is rich in protein and amino acids composition. In this study, it was used as a valuable protein source to produce antioxidant peptide. Enzymatic hydrolysis of wheat germ was done by pepsin. The hydrolysis parameters were optimized in production of wheat germ protein hydrolysates with the highest antioxidant activity using response surface methodology. Then the hydrolysates obtained under optimized conditions were fractionated by RP-HPLC and fraction that exhibited the highest ABTS radical scavenging was identified by nano-LC/MS/MS proteomics. The mathematical model presented a plateau region with maximum antioxidant activity at the following critical values: temperature = 37⁰C, time = 270 min and E/S ratio=1.58%. The results of sequencing showed that the purified peptide had the sequence of KELPPSDADW with the molecular weight of 1157.54 Da. This peptide had scavenging activity against DPPH (51±1.4%) and ABTS (86±1.1%) The results indicated that the peptide KELPPSDADW isolated from wheat germ protein has a strong antioxidant activity