Fig. 1.

In vitro selection strategy to identify DNA catalysts with phosphatase activity. Illustrated are the key selection and capture steps of each round. Each final deoxyribozyme has 40 particular nucleotides in its originally random N₄₀ region. The dashed covalent loop on the left side was required for the selection process but was dispensable for catalysis by individual deoxyribozymes. The loop was absent for all assays of individual deoxyribozymes.