Abstract
The solubility properties of tryptophan were observed in various solutions of the denaturants for β-lactoglobulin reported by Tanford, et al., and the effects of such 3rd component on the hydrophobic and the hydrophilic moieties of solute molecule was discussed on the basis of the enthalpy of mixing. As a result, it seemed possible to classify the denaturants into three types according to the balance of the effects on hydrophobic and hydrophilic moieties of tryptophan resulting in a change of solubility. In comparison with the existing data, the same classification might be extended to the denaturants according to their effects on the denaturation of β-lactoglobulin, and it was established that the solubility of tryptophan or the denaturation of β-lactoglobulin varies with the effects of additive (or denaturant) on hydrophobic and hydrophilic moieties of molecule, where the decrease in enthalpy of mixing is considered to be a predominant factor to result in the increase in solubility of tryptophan or to result in the denaturation of β-lactoglobulin.
