Exploring the antioxidant stability of sheep bone protein hydrolysate -identification and molecular docking

The aim of this study was to obtain sheep bone protein hydrolysates (SBPHs) with antioxidant activity from sheep bone byproducts and evaluate their stability and processing characteristics under different conditions. Then, the antioxidant peptides were identified and synthesized, and their antioxidant mechanism of action was investigated using molecular docking. The results showed that SBPHs obtained by alkaline protease hydrolysis had high antioxidant capacity and a high proportion of hydrophobic amino acids (41.33%). The antioxidant activity of SBPHs was intolerant to high temperatures and weakly resistant to acids and alkalis. NaCl improved the reducing power, sugars maintained the antioxidant activity, and metal ions reduced the antioxidant activity of SBPHs. SBPHs maintained higher antioxidant activity after simulated gastrointestinal digestion. Three fractions were isolated by ultrafiltration, among which P–I (MW < 3 kDa) had the strongest antioxidant activity. Liquid chromatography–tandem mass spectrometry (LC‒MS/MS) showed that 17 peptides with Peptide Ranker >0.85 were found in P–I. Among the synthesized peptides, VYPFPGPIPN had the strongest antioxidant activity, which was mainly exerted through hydrogen bonding, π-π stacking and π-alkyl bonding with Keap1. This study provides a reference for subsequent studies on the production, storage and antioxidant function utilization of SBPHs.