Enhancing tilapia fish myosin solubility using proline in low ionic strength solution

The effects of using proline to solubilise fish myosin under low ionic strength conditions were studied. After solubilising myosin in 0.1 M NaCl containing 5, 10, 15, and 20 mM proline, respectively, it was observed that more than 80% of the myosin was effectively solubilised using 10 mM proline. The addition of 10 mM proline lowered the surface hydrophobicity of myosin from 18.25 to 8.22 mg/g, increased the amount of beta-sheet structure from 33.87% to 46.88%, both of which facilitated solubilisation. As revealed by transfer free energy measurements, the interactions between proline and tyrosine and tryptophan residues were more favourable. Furthermore, the ability of proline to shield hydrophobic sites of myosin and to partially break disulphide bonds helped to form myosin oligomer aggregates. Transmission electron microscopy images verified the effects of proline on myosin proteins. A solubilisation mechanism based mainly on chemical interactions between myosin and proline was proposed.