The crystal structure (28) of the bimolecular quadruplex formed by the O.nova telomeric sequence d(G4T4G4) (PDB entry 1JPQ). (a) Overall topology is indicated by the ribbon representation in orange. The details of the molecular structure are also shown. Potassium ions are shown as green spheres. (b) A projection down the central channel, indicating the relative widths of the four grooves
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