Post-synthetically ligated ribozymes: an alternative approach to iterative solid-phase synthesis

To improve the overall yield of ribozyme synthesis, a convergent approach, based on the post-synthetic formation of an amino linker between two half-ribozymes was investigated. Borane.pyridine-mediated reductive amination of 3'-phosphoglycaldehyde-5'-half-ribozymes with 5'-aminohexyl-3'-half-ribozymes generated the corresponding amino-linked ribozymes in yields > 77% on different scales. The investigation of a variety of reducing agents is discussed together with a kinetic analysis of the selected coupling reaction. These post-synthetically ligated ribozymes exhibited slightly reduced in vitro catalytic activity and cell efficacy.