Solubility of salmon myosin as affected by conformational changes at various ionic strengths and pH

The relationship between solubility and conformational changes of salmon (Oncorhynchus tshawytscha) myofibrillar proteins at various Ionic strengths and pH was investigated using myosin as a model system. Solubility of myosin increased with increased KCl concentration up to 0.5M. Further increasing salt concentration resulted In a gradually reduced solubility. In the absence of salt, myosin was slightly soluble at pH>7 or <4. The increased solubility correlated with the Increased surface hydrophobicity and relative sulfhydryl content as well as the decreased α-helicity. At KCl >1.0M, myosin regained its helix structure with a concomitant loss of solubility due to the dominant hydrophobic interaction among nonpolar amino acid residues.