Molecular docking simulation combining with multi-spectroscopy techniques clarify how small molecule ligands bind to biomacromolecule: Myosin and aldehydes as a case study

The protein is an ideal food matrix binding volatile compounds. However, the synergistic effects between the protein rheological behavior and protein-ligand interactions on the small molecule ligand retention are not fully reported. This study clarified how aldehydes bind to myosin during the constant thermal treatment. The results presented that the myosin unfolded at 25-64 degrees C and were cross-linked to generate polymers at 75-79 degrees C. The alpha-helix fractions of myosin turned into beta-turn and random coil fractions, regulating the rheological behavior and exposing more binding sites with aldehydes. The binding affinity of myosin with aldehydes was confirmed. Notably, the fluorescence quenching behaviors of myosin were increased (p < 0.05) with the increase of pentanal concentration and heating temperature. Synergistic effects between the rheological behavior of myosin and the myosin-aldehyde molecular interaction might predominantly contribute to the aldehyde retention. The hydrophobic interaction, amino acid residues, free sulfhydryl groups, and hydrogen bond might be the key (non)covalent linkages for myosin to bind aldehydes. Thr125, Pro128, Trp131, and Val187 might be key sites between myosin and pentanal, among which the chemical forces were the conventional hydrogen bond, alkyl, pi-alkyl, and alkyl hydrophobic among them, respectively.