Dear Colleagues,

Beyond canonical double helical-based structures, such as B-DNA, A-DNA, and Z-DNA, recent decades have seen accumulating evidence of the existence and biological relevance of four-stranded nucleic acid structures, including G-quadruplexes (G4) and i-motifs. In the context of chemical biology, several studies have been devoted to the development of chemical and/or biophysical tools to understand the biological role of these high-ordered nucleic acid structures. Structural investigations have been achieved using NMR, RX, CD, and mass spectrometry analysis, which have, in particular, emphasized the high polymorphism associated with those tetrameric nucleic acid structures. The design of ligands that can selectively interact with G4 or i-motif nucleic acid structures has attracted substantial interest not only to realize chemical probes for G4 or i-motif structures but also to develop molecules with therapeutic properties. Concerning the design of ligands, several assays (in vitro, in cell, and in vivo) have been elaborated to select and study the most efficient ligands.

This Special Issue will cover the design of G4 or i-motifs ligands and their applications for a better understanding of the biological role of tetrameric nucleic acid structures, as well as for therapeutic uses. It also includes the development of chemical or biophysical tools to study these tetrameric structures, from in vitro to in vivo.

Prof. Eric Defrancq
Guest Editor

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• G-quadruplex
• i-motif
• chemical biology
• synthesis
• modeling
• biophysics
• probes