Structural and catalytic effects of an invariant purine substitution in the hammerhead ribozyme: implications for the mechanism of acid-base catalysis

Comparison of mutant and wild-type hammerhead ribozyme structures reveals active-site structural perturbations consistent with either a general base catalytic mechanism, as previously assumed to be operative in the hammerhead ribozyme, or a specific base catalytic mechanism, which may possess additional explanatory power.