Design of Hairpin Ribozymes for In Vitro and Cellular Applications

Following the discovery of catalytic RNA (1 ), a number of different ribozymes have been found. Most ribozymes carry out site-specific cleavage of the RNA phosphodiester backbone, although important exceptions may be emerging (2 ,3 ). The catalytic center and reaction site of several naturally occurring self-cleaving molecules have been dissected, and used to develop ribozymes that cleave external substrates (4 ). Because RNA structure is responsible for both catalytic activity and substrate recognition, ribozymes may be engineered to direct the inactivation of targeted cellular and viral RNAs through a catalytic cleavage mechanism (5 ).