title: Purification and characterization of antioxidant peptides from enzymatically hydrolyzed chicken egg white.
abstract: Egg white is considered as a rich source of high quality proteins with various bioactive peptide fractions. Enzymatic hydrolysis of proteins can be used to release bioactive fractions and different enzymes have different abilities in releasing such bioactive fractions depending on the enzyme's site of activity on a protein. In this study, several proteases were examined for their ability to release antioxidant peptides from hen egg white and protease P was selected based on the antioxidant activity and the digestion yield of the crude protein hydrolysate. A combination of several purification steps including ultrafiltration with low molecular weight cut-off membranes, cation exchange chromatography and reversed phase high performance liquid chromatography was used to purify 'protease P egg white hydrolysate'. Sixteen antioxidant peptides, which were derived from ovalbumin, ovotransferrin and cystatin were isolated from the most active fractions. Amino acid sequences of those peptides were determined using LC-MS/MS. Oxygen radical absorbance capacity (ORAC) values of selected short chain peptides were determined using synthetic peptides. Two peptides AEERYP and DEDTQAMP (Ala-Glu-Glu-Arg-Tyr-Pro and Asp-Glu-Asp-Thr-Gln-Ala-Met-Pro) showed the highest ORAC values. The results from this study indicate that egg white is rich in antioxidant peptides which can be used as a potential source for preparing bioactive ingredients using enzymatic hydrolysis followed by purification techniques.
authors.affiliation: Department of Agricultural, Food and Nutritional Science (AFNS), 4-10 Ag/For Centre, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Chamila
authors.initials: C
authors.lastname: Nimalaratne
authors.affiliation: Department of Agricultural, Food and Nutritional Science (AFNS), 4-10 Ag/For Centre, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Nandika
authors.initials: N
authors.lastname: Bandara
authors.affiliation: Department of Agricultural, Food and Nutritional Science (AFNS), 4-10 Ag/For Centre, University of Alberta, Edmonton, Alberta, Canada. Electronic address: jwu3@ualberta.ca.
authors.forename: Jianping
authors.initials: J
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000975:Antioxidants / Q000302:isolation & purification*; D002645:Chickens / Q000378:metabolism; D056148:Chromatography, Reverse-Phase; D003207:Conalbumin / Q000737:chemistry; D004529:Egg White / Q000737:chemistry*; D005260:Female; D008969:Molecular Sequence Data; D010047:Ovalbumin / Q000737:chemistry; D010446:Peptide Fragments / Q000302:isolation & purification*; D010447:Peptide Hydrolases / Q000737:chemistry*; D011492:Protein Hydrolysates / Q000737:chemistry; D059748:Proteolysis; D053719:Tandem Mass Spectrometry
chemical_list: D000975:Antioxidants; D010446:Peptide Fragments; D011492:Protein Hydrolysates; D003207:Conalbumin; D010047:Ovalbumin; D010447:Peptide Hydrolases
keywords: Antioxidant peptides; Chicken egg white; Chromatographic separation; Enzymatic hydrolysis; Ultrafiltration