Figure 3.

(Color online) Phase diagram of the nucleosome two-state system as a function of globular histone core charge and monovalent salt concentration of the surrounding solution. The interior region represents the wrapped state, ΔG < 0. The darker the interior region, the more stable the system is. The exterior region represents the unwrapped state, ΔG > 0. The darker the exterior region, the more unstable the system is. (White band) Interface between the two states is defined as |ΔG| < 5 kcal/mol. (dot, lower region of the graph) Physiological conditions at which the predicted stability of the nucleosome is ΔG = –38 ± 7 kcal/mol. (dashed arrows) Predicted trends that agree with experiment as conditions are changed from the physiological conditions.