Unconventional origin of metal ion rescue in the hammerhead ribozyme reaction: Mn(super 2+)-associated redox conversion of 2'-mercaptocytidine to cytidine

The metal ion specificity of the hammerhead (HH) ribozyme reaction upon sulfur substitution of the 2'-nucleophile is examine to characterize the behavior of 2'-mercapto oligonucleotides in biochemical reactions. The mechanistic evidence reveals that mercaptonucleotides can be used to generate carbon radical site specifically within structures RNA molecules, thereby providing possible probes for cross-linking and other biophysical studies.