Abstract
The structure of a hammerhead ribozyme does not change significantly in the presence or absence of Mg2+ ions, an indication that the role of Mg2+ ions is catalytic rather than structural. Accordingly, kinetics and molecular orbital calculations indicate that ribozymes are metalloenzymes. Kinetic analysis supports the idea that an important part of the binding energy (reflected in Kd) is utilized to provide the driving force for catalysis, so that the observed binding energy (Km reflected in) represents only what is left over after this utilization. It is also possible to produce nuclease-resistant ribozymes.
