Structural and functional responses of myofibrillar proteins from yellow croaker to plasma-activated buffer: evidence from a simulated PAW system.
Abstract
As a green non-thermal technology, plasma-activated water (PAW) generates reactive oxygen and nitrogen species (RONS) through plasma-liquid interactions and thereby affects the oxidation, conformation, and functionality of aquatic myofibrillar proteins (MPs). To investigate the regulatory effects of PAW on yellow croaker MPs, the original extraction buffer was replaced with plasma-activated buffer of different activation times, and the oxidation, conformation, and functional changes of MPs during chilled storage were evaluated. The results indicate that moderate PAW treatment induces mild oxidation and modulates protein conformation. PAW-30 s showed a lower bromophenol blue binding capacity (31.55 ± 0.95 μg), indicating limited intermolecular interactions and moderate aggregation that partially masked hydrophobic groups and improved structural stability. As the treatment time was extended to 60 s and 120 s, PAW further promoted the oxidation of thiol groups, altered surface hydrophobicity and intrinsic fluorescence characteristics, and enhanced the conformational rearrangement and intermolecular cross-linking of MP. SDS-PAGE results showed that the effects of PAW were primarily concentrated on the myosin heavy chain (MHC), as shown by MHC band weakening and increased high-molecular-weight aggregates, without obvious low-molecular-weight degradation. Molecular docking analysis further indicated that representative reactive oxygen species in PAW, H₂O₂ and O₃ can bind to specific regions on the MHC surface, thereby inducing local microenvironmental disturbances and oxidative modifications. Overall, PAW regulated yellow croaker MPs mainly through mild oxidation-induced conformational rearrangement and intermolecular cross-linking rather than extensive chain cleavage, with moderate activation being more favorable for maintaining MP structural stability and functional properties.