Abstract: The aim of this study was to explore the effect of hydroxyl radical oxidation on the degradation of myofibrillar proteins in the dorsal muscle of Coregonus peled. Four oxidation systems of 1 mmol/L H2O2 + 0.2 mmol/L FeCl3, 5 mmol/L H2O2 + 0.4 mmol/L FeCl3, 10 mmol/L H2O2 + 0.8 mmol/L FeCl3, and 20 mmol/L H2O2 + 1.0 mmol/L FeCl3 were set up, and the oxidation was carried out at ambient temperature for 0, 15, 30, 60 or 90 min, respectively. The optimal oxidation concentration and time were determined based on protein carbonyl content. Then the oxidized fillets were stored at 4 ℃ and sampled after 0, 1, 7, and 14 days to examine the degree of degradation of myosin heavy chain (MHC), actin, desmin and troponin-T of myofibrillar proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. The results showed that the optimal oxidation conditions were determined as incubation for 60 min in 5 mmol/L H2O2 + 0.4 mmol/L FeCl3. Compared with native MHC, the degradation of oxidized MHC was enhanced. Hydroxyl radical oxidation remarkably accelerated the degradation of MHC (P < 0.05). There was no significant change in the degradation of actin between the oxidized and non-oxidized groups after the same storage time (P > 0.05), suggesting that the natural degradation of actin was dominant during storage. According to the Western blotting analysis, the degradation efficiencies of both desmin and troponin-T in the oxidized group were lower than in the non-oxidized group, implying that hydroxyl radical oxidation inhibits the degradation of desmin and troponin-T. Overall, our results demonstrate that hydroxyl radical oxidation promotes the degradation of myofibrillar proteins of thick filaments, but has little influence on that of thin filaments and inhibits the degradation of cytoskeletal and junctional proteins.

Key words: Coregonus peled, hydroxyl radical, oxidation, myofibrillar protein, degradation