Abstract

The discovery of naturally occurring catalytic RNA (RNA enzymes, or ribozymes) in the 1980s immediately revised the view of RNA as a passive messenger that solely carries information from DNA to proteins. Because DNA and RNA differ only by the absence or presence of a 2'-hydroxyl group on each ribose ring of the polymer, the question of 'catalytic DNA?' arises. Although no natural DNA catalysts have been reported, since 1994 many artificial DNA enzymes, or 'deoxyribozymes', have been described. Deoxyribozymes offer insight into the mechanisms of natural and artificial ribozymes. DNA enzymes are also used as tools for in vitro and in vivo biochemistry, and they are key components of analytical sensors. This review focuses primarily on catalytic DNA for synthetic applications. Broadly defined, deoxyribozymes may have the greatest potential for catalyzing reactions in which the high selectivities of 'enzymes' are advantageous relative to traditional small-molecule catalysts. Although the scope of DNA-catalyzed synthesis is currently limited in most cases to oligonucleotide substrates, recent efforts have began to expand this frontier in promising new directions.