Nucleic acid conformation diversity: from structure to function and regulation

A Cationic Zinc Porphyrin as a Chiroptical Probe for Z‐DNA

“…Inspection of the structure of Z-DNA reveals that the alternate anti and syn conformation of nucleobases leads to exposure of guanine atoms N7 and C8, which are both shielded in the B form. [1,3] In Z-DNA, nitrogen atom N7 is available for coordination with transition-metal ions, as shown previously by IR, [34,35] and therefore can provide a site for axial coordination with the central zinc atom of 1. This hypothesis is corroborated by recent fluorescence studies which reported that the interactions of a cationic zinc(ii) porphyrin with polynucleotides caused a blue shift in the emission of the porphyrin despite the red shift in the absorption Soret band, [28,36] similar to what is observed here in the emission of 1·Z-DNA.…”

“…[1] The latter conformation is less common than the right-handed B-DNA because under physiological conditions Z-DNA has a higher energy. [2][3][4] Although the biological role of Z-DNA still remains to be clarified, it has recently been inferred that certain classes of proteins bind to it both tightly and specifically.…”

Conformational Control in Metallofoldamers: Design, Synthesis and Structural Properties

“…In rare cases, two diastereomeric structures of opposite helicity can be obtained for one compound by a thermodynamic inversion process. While helix inversion [22,23] between well-defined and wellcharacterized diastereomers is a biological phenomenon [24] found in natural systems, a similar process is not common in artificial systems. Following the idea that enantiomerically pure ligands will lead to metallofoldamers with single handed helical structure, Muller and Lisowski have reported a chiral nonaazamacrocycle amine, which coordinates Ln 3+ ions to form enantiopure helical complexes (Figure 7).…”

Synthesis and Structure of Dinucleotides with S‐Type Sugar Puckering and Noncanonical ϵ and ζ Torsion Angle Combination (ν2,ϵ,ζ‐D‐CNA)

“…[10,11] Together with the double-helix structure, nucleic acids can adopt alternative conformations such as bulges, hairpins, branched junctions, or U-turns. [12] These secondary structures are often characterized by non-Watson-Crick pairs or unpaired nucleotides and remarkable sugar-phosphate backbone distortions with torsion-angle conformations that are significantly different from those observed in regular double-stranded helices.…”