Figure 3.

(A) The effect of divalent cations and spermine on self-cleavage of clone 8 RNA. The RNA was treated with 50 mM sodium Mes buffer at pH 6.7 or pH 5.5, as indicated by + signs in the absence of any added metal ions (lanes 1 and 2) or in the presence of 2 mM MgCl₂ (lanes 3 and 4), 10 mM MgCl₂ (lanes 5 and 6), 10 mM MnCl₂ (lanes 7 and 8), 10 mM CaCl₂ (lanes 9 and 10), or in the presence of 0.5 mM spermine (lanes 11 and 12). (B) The effect of EDTA or increasing concentration of NaCl on self-cleavage. Reactions were carried out as described above in the absence of added metal ions (lanes 1 and 2) or in the presence of 50 mM NaCl (lanes 3 and 4), 250 mM NaCl (lanes 5 and 6), or 5 mM EDTA (lanes 7 and 8).