GMP-quadruplex Structures in Dilute Solutions and in Condensed Phases: An X-ray Scattering Analysis

The development of methodology for the chemical synthesis of oligonucleotides is the first step for producing not only the natural G-quadruplex sequences but also a large number of modified G-quadruplexes and other G-based supramolecular motifs; these methodologies will be summarized in this chapter. Natural or chemically modified G-motifs can be characterized by a variety of techniques. This chapter will not give an exhaustive list of methodologies, but simply shows how it is possible to gain structural information on G-quadruplexes by means relatively uncommon techniques such as: (i) differential pulse voltammetry; (ii) atomic force microscopy; (iii) dynamic light scattering; (iv) solution X-ray scattering; (v) temperature gradient gel-electrophoresis; (vi) Langmuir-Blodgett technique. Many other techniques are more usually adopted in G4 characterization (NMR, Scanning Tunnel Microscopy, Circular Dichroism, X-ray diffraction …) and examples of such applications can be found in the contributions to the other chapters of this book.