Purification and identification of antioxidant peptides from gelatin hydrolysates of unicorn leatherjacket skin

Antioxidant peptides from a gelatin hydrolysate of unicorn leatherjacket skin prepared using a partially purified glycyl endopeptidase were purified using Sephadex G-25 gel filtration, DEAE-cellulose anion-exchange and reverse phase high-performance liquid chromatography. The fractions with the highest ABTS radical scavenging activity were analyzed using UPLC-ESI-MS/MS to identify the peptide sequences therein. Four of the identified peptides, Glu-Pro-Gly-Pro-Val-Gly (555.27 Da), Leu-Pro-Gly-Pro-Ala-Gly (511.29 Da), Leu-Asp-Gly-Pro-Val-Gly (557.30 Da) and Glu-Gly-Pro-Leu-Gly (472.24 Da), were subsequently synthesized. Glu-Gly-Pro-Leu-Gly exhibited the highest antioxidant activity (4.95 μ mol TE/g solid). Therefore, peptides from unicorn leatherjacket skin gelatin hydrolysate could be further employed as functional food ingredient.