Examination of intermediates in globular protein unfolding by the tritium labeling method

Unfolding of polypeptide chain of ribonuclease A in urea and guanidinium chloride (GuCl) solutions under equilibrium conditions involves formation of intermediates whose properties (compactness and preservation of the most of the native hydrophobic core, secondary structures, and native-like folding of the polypeptide chain) correspond to the basic characteristics of the “molten globule” state. Intermediates are “damp” molten globules (with water molecules inside the globule). The examinations performed revealed pronounced distinctions in the properties of the intermediates, above all, in their compactness degrees.