Structural effect of association on protein molecules in partially folded intermediates.

Fluorescence and circular dichroism spectroscopy, small angle X-ray scattering and high performance liquid gel filtration have shown that oligomerization considerably affects the structural properties and conformational stability of partially folded intermediates of staphylococcal nuclease. Conformational transitions induced by different anions and association in the acid-unfolded protein are described. It is shown that association of non-native conformations of the protein molecule can be an additional structuring factor. The corresponding folding schemes and phase diagrams are suggested.