Abstract: The effect of oxidation on protein conformation and binding capacity of porcine myosin were investigated in vitro using a FeCl3/Asc/H2O2 hydroxyl radical oxidation system. The contents of total and reactive sulfhydryl groups, secondary structure and surface hydrophobicity were detected as a function of H2O2 concentration, and the interactions between porcine myosin and four typical aldehyde compounds responsible for the flavor were investigated. It was demonstrated that the protein conformation was significantly affected by H2O2 concentration. The content of reactive sulfhydryl groups was significantly decreased while surface hydrophobicity was significantly increased with the increase of H2O2 concentration (P < 0.05). The contents of total sulfhydryl groups and α-helix were significantly decreased (P < 0.05) while the binding capacity between myosin and aldehyde compounds was significantly increased in the H2O2 concentration range from 0 to 5 mmol/L (P < 0.05). The α-helix content was significantly increased while the binding capacity of myosin was significantly decreased with increasing H2O2 concentration to 10 mmol/L (P < 0.05). The binding capacity of myosin was significantly increased again with further increasing H2O2 concentration to 20 mmol/L (P < 0.05). The main binding forces between aldehyde compounds and myosin were hydrogen bond and hydrophobic interaction. Stronger hydrogen bond and/or hydrophobic interaction led to a higher binding capacity of myosin to aldehyde compounds.

Key words: radical oxidation, H2O2, myosin, protein conformation, flavor binding capacity