Figure 4. The effect of salts on depurination from N30.

(a) Depurination in the NaCl buffer (pH 1.4); (b) Depurination in the MgCl₂ buffer (pH 1.4); (c) Depurination in the NaCl buffer (pH 5.9); (d) Depurination in the MgCl₂ buffer (pH 5.9). The pH values of the buffers were adjusted to 1.4 (±0.1) or 5.9 (±0.2) with an aqueous solution of HCl. The reaction was performed for 60 min at 37°C (pH 1.4) or 24 h at 80°C (pH 5.9) to limit the percentages of depurination less than 20%. In each chart, the depurination rate constant of N30 in the pure HCl buffer was served as the reference.