Fig. 3

ATP-selective nucleation-growth of 1. a CD intensity, b CD spectra, and c absorbance spectra of 1 with various phosphates (c = 2 × 10⁻⁵ M, HEPES/CH₃CN, 90/10, v/v, 0.9 equiv. ATP, AMP, ADP, GTP, UTP and CTP, 30 °C). Final snapshots of d, ATP and e, GTP-bound stacks of 1 (ATP-1 and GTP-1) obtained from MM/MD simulations. Zoomed images in d and e show intermolecular H-bonding between the triphosphates. Zinc atoms have been depicted as balls of two different colours (magenta and yellow) for easy identification of the helicity in the oligomer. Molecules of 1 are depicted as black sticks (in d and e), while ATP and GTP are in red. In zoomed images of d and e, intermolecular H-bonds are shown as dashed light blue lines. Each ATP/GTP molecule is depicted in a distinct colour to make it obvious that the hydrogen bonds are intermolecular in character. Comparison between f, intramolecular H-bonds, g, intermolecular H-bonds and h, π−π distance between two adjacent molecules of 1 in ATP-1 and GTP-1 simulated assemblies. The peripheral molecules in the stack are relatively more flexible, which leads to a higher π−π distance, giving a bimodal signal in the case of ATP-1 assembly. On the other hand, in the case of the GTP-1 assembly, the molecules in stack are not well packed, which gives rise to a multimodal distribution