Figure 2.

(A) Hemin/G-quadruplex-dopamine aptamer nucleoapzyme structures where in configuration I the catalyst is linked through a TATA tether to the 5′-end of the aptamer. In configuration II, the catalyst is tethered to the 5′-end of the aptamer through a single A bridge. In configuration III, the catalyst is linked to the 3′-end of the aptamer through a TATA tether. Configuration IV represents the control system, where the hemin/G-quadruplex catalyst is separated from the aptamer scaffold. The reaction driven by the systems corresponds to the hemin/G-quadruplex-catalyzed oxidation of dopamine (1) by H₂O₂ to aminodopachrome (2). (B) Rates of oxidation of dopamine (1) by H₂O₂ at different concentrations of dopamine (1): (a) nucleoapzyme configuration I, (b) nucleoapzyme configuration II, (c) nucleoapzyme configuration III and (d) control system consisting of the separated components (configuration IV). (C) Molecular dynamics energy-minimized structures of (I) nucleoapzyme in configuration I and (II) nucleoapzyme in configuration III.