| Abstract: | The effects of combining two different alcohols on the transition temperature of ribonuclease were investigated. It appears that at 60°C the combined effects on the transition temperature of ribonuclease of two different alcohols are equal to the algebraic sum of the effects of each individual alcohol. This holds true for a combination of two monohydric alcohols, two polyhydric alcohols and a combination of a monohydric and a polyhydric alcohol. At lower temperatures only the effects of the combinations of two polyhydric alcohols show additivity. The combined effect of a polyvalent alcohol and a monovalent alcohol at low temperature is surprisingly higher than the algebraic sum of the effects of the individual alcohols. The polyhydric alcohol enhances the hydrophobic effect of the monovalent alcohol for temperatures up to 50°C. Obviously the polyhydric alcohol perturbs the water structure at these low temperatures, which leads to the intensifying of the interhydrophobic interactions. Furthermore, the combined effect of two different monovalent alcohols with different hydrophobic effects does not show additivity at low temperatures. The single (OH) group of the weakest hydrophobic alcohol enhances the hydrophobic effect of the potentially strongest hydrophobic alcohol. |
