A specific antioxidant peptide: Its properties in controlling oxidation and possible action mechanism.

Marine byproducts have become popular research themes due to their biological significance. The black sharkskin protein hydrolysate-based antioxidant peptides were firstly investigated in this study. The black sharkskin-derived novel antioxidant peptide demonstrating 81.05% free radical scavenging activity to ABTS at 500 μg/mL, was identified to be Ala-Thr-Val-Tyr (ATVY). The crucially antioxidant interaction site of ATVY action on ABTS was determined to be Tyr in the N-terminal. ATVY reacted with ABTS to generate polyphenol-derived adducts which subsequently degraded into a purple compound. The MS/MS showed it was formed by covalently bonding through the phenol group of ATVY to the N group of ABTS. The free radical scavenging kinetics of ATVY on ABTS demonstrated a two-phase reaction process. These findings reveal the action mechanism of ATVY on ABTS, implying ATVY can be incorporated in the production of antioxidant food additives.