bpDNase I binding site occupancy by cation species.

Amino acids involved in the coordination sphere (AAcs) of the four bpDNase I cation-binding sites (Figure 1 and 3). The percentage of simulation time (%tocc) corresponding to effective coordination of each cation was calculated for the last 20 ns of the relevant trajectories (Table 2). This amounts to 20 ns for Na+ (I, II, IVb), 40 ns for Na+ (IVa) and Mg2+ (IVb), 60 ns for Na+ (III) and Mg2+ (IVa), 80 ns Mg2+ (III) and 120 ns for Ca2+. The interaction between Mg2+ and His252 is either direct or mediated by a water molecule. N.A.: not applicable.