In vitro selection of a deoxyribozyme that can utilize multiple substrates.

Deoxyribozymes that could catalyze the formation of an internucleotide phosphorothioester linkage were selected from a random sequence pool. During the course of the selection, the pool was successively challenged with five oligonucleotide substrates, each of which terminated in the same hexanucleotide sequence. Selected deoxyribozyme ligases could use all five substrates, albeit to different degrees, and appeared to form secondary structures that allow differential pairing between the deoxyribozyme and each substrate. These results suggest that early replicases may have been able to bind a variety of oligonucleotide substrates while catalyzing ligation via a common junction.