Figure 7.

The effects of various metal cations on class II ribozyme function. (A) Representative PAGE (denaturing 10%) separation of RNAs resulting from the incubation of trace amounts of 5′-³²P-labeled class II ribozymes in the presence of 100 μM Be²⁺, La²⁺ or Cu²⁺ under standard reaction conditions at 23°C for 5 min. Reactions were conducted in the absence (−) or presence (+) of 100 μM CoCl₂. Open and filled arrowheads identify bands corresponding to 5′-³²P-labeled full-length precursor (Pre) or the 5′-cleavage product (Clv), respectively. Bracket identifies bands corresponding to uncleaved precursor RNAs whose gel mobility is altered, presumably due to strong interactions between RNA and the cation being tested. The results for Be²⁺, La²⁺ or Cu²⁺ are typical of that for cations that are disruptive, inhibitory and non-activating, respectively. (B) Summary of the various metal cations tested and their effects on class II ribozyme activity in the absence and presence of 100 μM CoCl₂. Results from metal assays with Class II ribozyme are shown. Unless otherwise indicated, the metal form tested is the 2⁺ ionic species.