Abstract:The preparation of yak skin peptides (YSP) are studied through enzymatic hydrolysis, followed by synthesis of its complex with (-)-epigallocatechin gallate (EGCG). The interactions between YSP and EGCG were investigated using turbidity, particle size, zeta potential, multispectral analysis, and molecular docking techniques. In addition, their in vitro antioxidant activities and digestion properties were evaluated. The results indicated that the highest yield of YSP reaching 67.96%, was achieved through trypsin hydrolysis, with hydrophobic amino acids comprising 54.01% of the total amino acids. As the concentration of EGCG increased, both, turbidity and particle size of the system increased, and a significant change in surface charge was observed. Meanwhile, ultraviolet absorption gradually increased and fluorescence quenching was significantly enhanced, suggesting strengthening of the YSP and EGCG molecular interaction, leading to the formation of a relatively stable complex. Fourier transform infrared (FT-IR) spectroscopy revealed slight changes in the secondary structure of the complex, with potential interactions occurring between N-H and C=O groups. More importantly, the YSP-EGCG complex exhibited stronger antioxidant activity than either component alone. EGCG modification effectively protected and enhanced the antioxidant activity of YSP during digestion. The peptide sequence SGDRGETGPAGPAGPIGPV was identified by mass spectrometry, and molecular docking confirmed that the binding interaction between YSP and EGCG was primarily driven by hydrogen bonds. This study demonstrates that EGCG can enhance the antioxidant activity and stability of YSP, providing a foundation for the application of YSP and its complexes in food or cosmetic products.
