Effects of hydroxyl radical oxidation on the structural and functional properties of mutton myosin

To research the impact of free radical oxidation on myosin, we established a hydroxyl radical oxidation system using iron/hydrogen peroxide/ascorbic acid. By varying hydrogen peroxide concentrations (0, 0.5, 1, 5, 10, 20 mmol.L-1), we achieved different oxidation levels of myosin and investigated the effects on its structural and functional characteristics. The results showed that when the H2O2 concentration was 20 mmol.L-1, compared with the control group, the carbonyl content of myosin was 2.376 times higher, the sulfhydryl content was decreased by 37.02%, the surface hydrophobicity was increased by 59.13%, the solubility was decreased by 19.54%, and the turbidity was significantly increased (P < 0.05). Myosin emulsification, emulsification stability, and foaming capacity initially increased and then they diminished, and the maximum value was reached when the H2O2 concentration was 5 mmol.L-1, whereas foaming stability remained relatively unchanged. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis research revealed increased crosslinking and protein polymerisation in oxidised myosin. The secondary structure of myosin measured by Fourier infrared spectroscopy showed that the α-helix content decreased by 14.41% and the β-fold content increased by 44.50%. These results suggested that oxidative modification alters the structural and functional properties of myosin, providing valuable insights for its structural and functional analyses.