... using the hammerhead ribozyme showed that instead of having a coordinated stimulating effect on ribozyme activity, Na+ ions inhibit divalent ion mediated ribozyme reactions at lower concentrations, ... evolution EMBO J 16, 3289–3302 25 Ikawa, Y., Naito, D., Aono, N., Shiraishi, H & Inoue, T (1999) Trans-activation of the Tetrahymena group I intron ribozyme via a non-native RNA RNA interaction Nucleic ... Takagi, Y., Kasai, Y., Inoue, A. , Baba, T & Taira, K (2002) Existence of efficient divalent metal ioncatalyzed and inefficient divalent metal ion-independent channels in reactions catalyzed by hammerhead...