Quartets, guanine

It has been suggested that zinc ions prevent formation of DNA quadruplexes containing guanine quartets by binding to the guanine N7 and 06. The quadruplexes are believed to be important to a number of areas of the genome including telomeres.179... 

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.

Fig. 10.13 The guanine-silylated conjugate 5 self-associates in the presence of alkali-metal cations to form hexagonal nanorod hybrids, presumably formed by G-quartet-based interactions.

Inhibition of HIV-1 Integrase 3 Processsing (3 -Proc), Strand Transfer (ST) and HIV-1RF Cytopathicity (HIV-1rf) by Some Guanine Quartets in Cell Cultures... 

Sreenivasachary, N. Lehn, J.-M. Gelation-driven component selection in the generation of constitutional dynamic hydrogels based on guanine-quartet formation. Proc. Natl. Acad. Sci. U.S.A. 2005,102, 5938-5943. 

Figure 19. Metalated cyclic nucleobase quartet containing dianionic guanine and monoanionic adenine nucleobases. [Reprinted with permission from M. S. Liith, E. Freisinger, F. Glahe, and B. Fippert, Inorg. Chem., 37, 5044 (1998). Copyright American Chemical Society.]...

S. Metzger, B. Lippert, A metalated guanine,cytosine base quartet with a novel GC pairing pattern involving h(5) of c. J. Am. Chem. Soc. 118, 12467-12468 (1996)... 

Most remarkably, whereas metal-templated guanine self-assembly favors tetramers (G-quartets), iso-guanine tends to form cyclic pentameric arrays in the presence of a suitable metal, such as Cs+ [38], The angle between the two... 

On the other hand, in the formation of guanine quartet-based hydrogels, it was shown that the system selected those components that generated the most stable gel [50] (see Fig. 5 in [50]). Such a self-optimization behavior may be of much deeper general significance, namely for prebiotic chemical evolution, whereby selection is driven by phase cohesion, the entity selected being that giving the most stable... 

Fig. 9 Cation-template resolution of a dynamic supramolecular guanine system in which G-quartet is reversibly exchanging with linear ribbons followed by a secondary irreversible sol-gel selection of G-quadruplex hybrid materials...

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. 

Otero R, Schock M, Molina LM, Loegsgaard E, Stensgaard I, Hammer B, Besenbacher E. Guanine quartet networks stabilized by cooperative hydrogen bonds. Angew. Chem. Int. Ed. 2005 44 2270-2275. 

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