Table 1.

McCl₂ dependence of binding d(AnTnGnAnCn)rU and P-8/4x

[MgCl2], mM	kd, nM
3	175
4	94
5	99
15	31 (16)*

Assays were run in HxMg buffer, consisting of 50 mM Hepes (25 mM Na⁺) at pH 7.5, 135 mM KCl, and x mM MgCl₂. Each reported value is the average of at least two independent assays. The dissociation constant, K_d, was determined by direct band-shift gel electrophoresis. 

^*K_d was determined by competition band-shift gel electrophoresis (11).