Self Guanine Quadruplex

Self-Organization of the Guanine Quadruplex in Hybrid Supramolecular Polymers... 

Triple-helix formation by G-rich oligonncleotides is supported by Mg + but strongly inhibited by physiological concentrations of certain monovalent cations, especially K+, most likely dne to oligonncleotide self-association in competitive structures such as guanine-quadruplexes. " Variation of the cation enviromnent can differentially promote the assembly of multistranded nncleic acid structural alternatives. For example, by specifically counteracting the induction/stabilization of quadruplex structures by potassium ions, certain divalent ions (i.e. Mn +, Co +, and Ni + but not Mg +) at low millimolar concentrations allow triplex formation in the presence of 150mMK+. In contrast, certain mono- and divalent metal ions can promote the transition from Watson-Crick duplexes to G4 quadruplex structures relatively efficiently K" " > Ca + >... 

Fig. 10.12 (A) The cation-templated hierarchic self-assembly of guanine alkoxysilane gives the C-quartet and (B) the G-quadruplex transcribed in solid hybrid materials by the sol-gel process.

For all these reasons, the guanine building blocks and the sol-gel chemistry were used as molecular precursor to conceive hybrid chiral materials at nanometric and micrometric scales. Our efforts involved the synthesis and the self-assembly of a guaninesiloxane monomer Gsi (Fig. 3) in the G-quartet and G-quadruplex supramolecular architectures (Fig. 6), which are fixed in a hybrid organic-inorganic material by using a sol-gel transcription process, followed by a second inorganic transcription in silica, by calcination. 

The formation of a quadruplex simply requires four guanine repeats to selfassociate. The simplest topology is formed by the self-association of four DNA strands in solution containing short guanine runs, for example... 

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