Figure 8
Ion binding to the 24 bp DNA duplex. The number of excess Na+ (squares) and Mg2+ (circles) ions and depleted Cl- ions (triangles) per DNA was measured by AES (see Materials and methods) as a function of MgCl2 concentration in 20 mM NaCl background. Theoretical predictions were obtained from PB calculations using the PDB coordinates (thin, solid lines) or the reconstructed bead model with uniformly assigned charges (thick, dashed lines). |