A deoxyribozyme that synthesizes 2

ABSTRACT RNA molecules with internal 2,-triphosphate,on another,RNA substrate. The pref- erence,for the,branch-site,nucleotide,is U . C ffi A . G, although all four nucleotides are tolerated with useful ligation rates. Nearly all other nucleotides elsewhere,in both RNA substrates,allow ligation activ- ity, except that the sequence requirement for the RNA