Figure 4.

Artificial phylogeny comprised of deoxyribozyme variants isolated after five rounds of selection beginning with mutagenized NTP-A2. Nucleotides depicted correspond to the original random-sequence domain. The donor domain (not shown) was found to vary, and each conforms to one of the following states represented by zero through four asterisks, respectively: GGAAAGATGCGAC (original), GGAAAGATG-GAC, GGAAAGATGTGAC, GGAAAGATGGGAC, and GGAAAGAAGCGAC. Overlined nucleotides identify four regions (I–IV) of conserved tracts of guanosine residues. (^†) identifies variant “NTP-A2.1,” which was used in further analyses. Reactions were performed for 1 hr by using 100 μM ATP for first two rounds and for 5 min by using 10 μM ATP for the final three rounds.