Molecular interactions between natural pungent spices and grass carp myofibrillar protein: Conformational remodeling deciphered through multiscale characterization

This study investigated interactions between capsaicin (CAP), piperine (PIP), allicin (ALL) and grass carp myofibrillar protein (MP) regarding protein conformational changes. While the bioactivities of these pungent compounds are recognized, a systematic understanding of their diverse binding patterns and consequent conformational remodeling of MP remains limited. The binding patterns and regulatory mechanisms were systematically evaluated through multispectral analysis, physicochemical characterization, and molecular docking simulations. Results demonstrated that CAP binding coincided with MP aggregation, increased surface hydrophobicity, and elevated random coil content, alongside the weakest binding energy (−6.9 kcal/mol). These effects were consistent with a binding pattern dominated by hydrophobic interactions and dynamic quenching. PIP binding correlated with conformational loosening and maintained colloidal dispersibility but limited stabilization, associated primarily with hydrogen bonding and static quenching (K q  > 9.0 × 10 12  L/(mol·s)). ALL binding at higher concentrations corresponded to conformational compaction, increased α-helix/β-sheet content, and enhanced structural stability, with the strongest binding affinity (−19.82 kcal/mol). These changes aligned with a mechanism involving covalent bonding synergized by hydrogen/hydrophobic interactions. These findings provide molecular-scale insights into pungent spice-MP interactions, offering strategies for optimizing spicy food systems.