Structural Changes and Molecular Mechanisms of Myosin Induced by Oxidative Modification With Malondialdehyde

This study investigated the structural changes and molecular mechanisms induced by the oxidation of pork myosin by malondialdehyde (MDA). The effects of varying MDA concentrations on carbonyl content, sulfhydryl content, disulfide bond content, surface hydrophobicity, Ca²⁺-ATPase activity, free ammonia content, UV-visible spectral characteristics, SDS-PAGE profiles, and Fourier transform infrared spectroscopy (FTIR) were systematically evaluated. Additionally, molecular docking techniques were employed to predict potential oxidative modification sites on the myosin molecule. The results showed that MDA oxidation significantly altered the chemical structure and physicochemical properties of myosin. As MDA concentration increased, carbonyl content increased, sulfhydryl content decreased, disulfide bond content increased, surface hydrophobicity was enhanced, and notable conformational changes occurred. These alterations led to an initial activation followed by inhibition of Ca²⁺-ATPase activity. SDS-PAGE analysis revealed MDA-induced myosin aggregation at higher concentrations, while FTIR results indicated a reduction in α-helix content and a corresponding increase in β-sheet and random coil structures, suggesting a transition from ordered to disordered or aggregated states. Molecular docking analysis further confirmed that MDA formed hydrogen bonds and hydrophobic interactions with key residues PHE-760 and LYS-759 in myosin, promoting oxidative modifications. Overall, this study provided a molecular-level understanding of MDA-induced oxidative alterations in myosin and offered insights that may help in controlling oxidative damage and quality deterioration in muscle-based food systems.