부산대학교 도서관

Structural proteins such as spider silk and silkworm silk are generally poorly soluble in aqueous and organic solutions, making them difficult to manipulate in manufacturing processes. Although some organic acids and alcohols, such as formic acid and hexafluoroisopropanol (HFIP), effectively solubilize poorly soluble proteins, little is known about their protein solubilization mechanism. In this study, the solubility of N -acetyl amino acid amide compounds in organic solvents—formic acid, acetic acid, HFIP and isopropanol—was measured to clarify the protein solubilization mechanism at the amino acid residue level. On the basis of thermodynamic analyses of the solubility in terms of the transfer free energy (from water to organic solvents), every organic solvent was found to be effective in thermodynamically stabilizing hydrophobic amino acid side chains in the liquid phase. Formic acid and HFIP were comparably effective in the stabilization of the polypeptide backbone, whereas acetic acid and isopropanol were ineffective. Therefore, the significant solubilizing effect of formic acid and HFIP on the structural proteins was attributed to their favorable interactions with hydrophobic amino acid side chains and with the polypeptide backbone of the proteins. The present findings are useful for the optimization of protein manipulation and amino acid sequence design. [Display omitted] • Formic acid and fluoroalcohol are effective in solubilizing structural proteins. • The protein solubilization mechanism should be elucidated at amino acid level. • The solubility of N -acetyl amino acid amides was determined in organic solvents. • Organic solvents thermodynamically stabilize hydrophobic amino acid side chains. • Formic acid and fluoroalcohol stabilize the polypeptide backbone. [ABSTRACT FROM AUTHOR]