The solubility and conformational characteristics of porcine myosin as affected by the presence of l-lysine and l-histidine

The influence of l-lys and l-his on the solubility, surface hydrophobicity, sulphydryl content and conformational characteristics of porcine myosin solubilised in high (0.6 M), physiological (0.15 M) and low (1 mM) ionic strength solutions were explored. The solubility of myosin was increased in the presence of l-his and/or l-lys in all ionic strength solutions used. The presence of l-his and l-lys caused increases in the surface hydrophobicity and reactive sulphydryl content (p < 0.05). Circular dichroism revealed a significant decrease of α-helical content with an increase of random coils, β-turns and β-sheets in the presence of l-his and/or l-lys. These results demonstrate that the introduction of l-lys and l-his causes the unfolding of myosin, resulting in loss of α-helical structure, which is followed by increases in random coils, β-turns and β-sheets, which exposes buried hydrophobic and sulphydryl groups to the myosin surface, ultimately increasing the solubility of porcine myosin.