Bromelain-induced physicochemical and structural changes in beef myofibrillar proteins and their molecular interaction mechanisms

Abstract

This study evaluated bromelain-induced structural changes in beef myofibrillar proteins (MP) and explored related molecular mechanisms. Bromelain treatment markedly changed MP physicochemical features and structural conformation, facilitated aggregate dissociation, and increased dispersion and solubility (P < 0.05). The 0.50% bromelain treatment showed the greatest effect, increasing MP solubility to 81.53% and reducing the PDI to 0.338 ± 0.036. It also exposed previously buried hydrophobic moieties and thiol groups, reduced the proportion of ordered structures, and shifted MP from a compact, ordered conformation toward a loose, disordered state. Molecular docking indicated that bromelain bound stably to myosin heavy chain (MHC), primarily via hydrogen-bond interactions, with a binding energy of −12.4 kcal/mol. Molecular dynamics simulations further revealed that bromelain binding reduced the structural stability of MHC and promoted a looser conformation. These results offered theoretical support for employing bromelain to improve meat tenderness and regulate product quality.