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. 2010 Sep 8;99(5):1577–1585. doi: 10.1016/j.bpj.2010.06.046

Figure 2.

Figure 2

(Color online) The two states of the nucleosome in the idealized geometry model: the fully wrapped nucleosome core particle and the globular histone core plus free DNA. The computed stability, ΔG, corresponds to the unwrapped state→wrapped state transition (Large dashed arrows pointing from top to bottom). (A) The charge distribution of the idealized geometry model. For all cylinders, the total charge is uniformly distributed on the side surface; the top and bottom surfaces are excluded. The labels QC, QD1, and QD correspond to the total charge of the globular histone core, the charge of the DNA not exposed to the solvent, and the total charge of the DNA. (B) The potentials and geometric dimensions used in the model. The labels RN, LN, RC, LC, RD, and LD correspond to the radii and lengths of the nucleosome, histone core, and DNA, respectively. The value ϕI specifies the potential at the external surface of the nucleosome. The value ϕII is the potential at the interface between the histone core and DNA. The value ϕIII represents the potential at the external surface of the histone core, and the value ϕIV is the potential at the external surface of the unwrapped DNA. See Eqs. 6–9 for the exact forms of these potentials.