Solubility of Proteins in Nonaqueous Solvents

A wide spectrum of proteins can be directly dissolved in any one of a number of strongly protic solvents. This has been demonstrated particularly for dichloroacetic acid (Yang and Doty, 1957), hydrofluoric and tri- 

Solvent Dielectric constant B.P. M.P. Density Refractive index ( n) Viscosity (cp) References 

Audricth, L. F., and Kleinberg, J. (1953). Nonaqueous Solvents. Wiley, New York. 

International Critical Tables. (1929). McGraw-Hill, New York. 

Hcilbron, I., and Bunbury, H. M. (1963). Dictionary of Organic Compounds, revised ed. Oxford Univ. Press, London and New York. 

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In preliminary surveys of the solubilities of proteins in nonaqueous solvents, the solvent has generally been added directly to the solid protein. After suitable agitation, those mixtures that appeared homogeneous were classed as solutions. In this manner a number of interesting binary systems have been discovered. Some proteins which are not very soluble in aqueous media are quite soluble in a wide range of suitable nonaqueous... 

The solubility of proteins in nonaqueous solvents makes it possible to study them in homogeneous solution at temperatures below the freezing point of aqueous solutions, since many pure nonaqueous solvents have freezing points well below 0°C (Table I). Freezing temperatures can be lowered even further by the use of solvent mixtures. This opens a new dimension in protein chemistry the significance of which can only dimly be appreciated at the present time. Several possible problems of interest may be mentioned, however. 

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