A preliminary study of the properties of proteins in some nonaqueous solvents

1. 1. Solubility tests have been performed with 23 protein preparations and sodium deoxyribonucleate in 37 nonaqueous solvents. Most of the proteins were soluble in hydrazine and ethylenediamine, and other successful solvents, in the order of decreasing effectiveness, were propylenediamine, formamide, dimethyl sulfoxide, ethylene glycol, and N-methylacetamide. Insulin and zein were dissolved in 13 and 15 solvents, respectively, with a unique parellelism that suggests some similarity in the structures of the two unrelated proteins. DNA is soluble in hydrazine, ethylene glycol, and formamide. 2. 2. In freshly prepared hydrazine and ethylenediamine solutions, the results of solubility, ultracentrifuge, and viscosity experiments indicate that protein molecules are unfolded and elongated compared to their structures in water solution. In hydrazine, DNA molecules appear to undergo some structural alteration which requires further study. 3. 3. Trypsin dissolves in formamide and dimethyl sulfoxide, and retains its enzymatic activity when recovered from these solutions and placed into aqueous media. 4. 4. Osmotic-pressure measurements with insulin in dimethylformamide and dimethylacetamide demonstrate that the fundamental covalently bonded unit of the molecule has a molecular weight of about 6000, and therefore contains one A and one B chain.