Influence of self-assembly on the reactive sulfhydryl and antioxidant activity of aggregation-prone ovalbumin-derived peptides

Ovalbumin-derived peptides IFYCPIAIM, NIFYCPIAIM and YCPIAIMSA, containing a common region YCPIAIM, were previously identified as aggregation-prone peptides with variable fibril formation. In this study, we elucidated self-assembly mechanisms of the peptides, by determining the influence of self-assembly on sulfhydryl group accessibility. The free sulfhydryl group content and antioxidant capacity results demonstrate that the peptides assemble into β-sheets, possibly involving hydrogen bonding with the sulfhydryl groups. NIFYCPIAIM, IFYCPIAIM and YCPIAIMSA, in decreasing order, had the largest particle size, thioflavin T fluorescence, reactive sulfhydryl group content, and antioxidant activities. This demonstrates that the reactive sulfhydryl group content, which is influenced by the cysteine residue position relative to the N-terminal of the peptide, is dependent on fibrillation. Rheological studies further demonstrated the non-Newtonian shear-thinning behavior of the peptides. The results provide valuable insight on peptide self-assembly, which is imperative for future design of bioactive hydrogels with promising biomechanical properties for biomaterial applications.