Figure 4.

Sulfate- and protein concentration-dependent conformational “phase” diagram for the conformational states of staphylococcal nuclease at 23°C and pH 2.5. The conformational space consists of U_A, A₁, globular dimers with more secondary structure than the monomer, and globular oligomers with native-like secondary structure content. The continuous lines show the boundaries between these states. Boundaries were determined on the basis of the midpoint (C_m) values of the corresponding Na₂SO₄-induced transitions at fixed protein concentrations (squares), or midpoint (C_m) values of transitions induced by the increasing in protein concentration at fixed sulfate content (circles). The shaded area represents the conditions at which precipitation occurs.