Figure 7.

Secondary structure prediction for enzyme catalytic core of clone 32 following analysis using RNA and DNA secondary structure prediction using M-fold software (48). Circled letters correspond to ribonucleotides, uncircled letters correspond to deoxynucleotides and starred letters correspond to modified nucleotides 1 (U*) and 2 (A*). Arrows indicate the sites of RNA cleavage. A 6–8 nt triplet AAG near the 5′ end was forced to interact with a 3′-TTC-5′ triplet at the 3′ end to form a double helix prior to the folding calculation.