l-Arginine and l-Lysine Alleviate Myosin from Oxidation: Their Role in Maintaining Myosin’s Emulsifying Properties

This study investigated the alleviative effects of l-arginine and l-lysine on the emulsifying properties and structural changes of myosin under hydroxyl radical (·OH) stress. The results showed that ·OH decreased the emulsifying activity index and emulsifying stability index but increased the creaming index and droplet size of a soybean oil–myosin emulsion (SOME). Confocal laser scanning microscopy demonstrated that ·OH caused larger and more inhomogeneous SOME droplets. l-Arginine and l-lysine effectively alleviated ·OH-induced destructive effects on the emulsifying properties of myosin. In addition, ·OH increased the extent of protein carbonylation and dityrosine formation, surface hydrophobicity, and β-sheet content, but decreased the tryptophan fluorescence intensity, solubility, total sulfhydryl, and α-helix content of myosin. Although l-lysine increased dityrosine fluorescence intensity, l-arginine and l-lysine effectively alleviated the aforementioned structural changes of myosin. Therefore, l-arginine and l-lysine could mitigate ·OH-induced structural changes of myosin, which enabled myosin to maintain its emulsifying capacity under oxidative stress.