Bulky cations greatly increase the turnover of a native hammerhead ribozyme

Methods to facilitate the catalytic turnover of ribozymes are required for advancing oligonucleotide-based technologies. This study examined tetraalkylammonium ions for their ability to increase the efficiency of catalytic turnover of a native hammerhead ribozyme. Kinetic analysis showed that large tetraalkylammonium ions significantly increased the turnover rate of the ribozyme and was much more effective than poly(ethylene glycol) (PEG) and urea. The magnitude of the rate increase depended on the concentrations of Mg(2+) and tetrapentylammonium ions, and the rate was enhanced by more than 180-fold at the optimal concentrations of these salts. The results provide physical insights into interactions of ribozymes with large cationic molecules through electrostatic forces and steric hindrance.