Stefan Loic

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/62165

## **Abstract**

Catalysis of chemical reactions is crucial for both chemical industry and research. How‐ ever, scientists are not the first ones to use catalysts in their laboratory. In fact, they are also essential for nature which designs plenty of biocatalysts, playing a pivotal role in liv‐ ing systems. For a long time, it was thought that only enzymes had this property. How‐ ever, since the beginning of the 1980s, it is known that ribonucleic acids (also termed RNA) can acquire this ability, making them compulsory for key reactions (*e.g.*, for the translation of messenger RNA in the ribosome). Based on that, chemists designed several synthetic DNA catalysts (termed DNAzymes) for a large variety of reactions and applica‐ tions. Among the DNA structures used, G-quadruplexes are guanine-rich noncanonical DNA structures (*i.e.*, differing from duplex DNA) composed of native G-quartets and particularly interesting for their ability to catalyze reactions of peroxidation. This peroxi‐ dase-mimicking system found plenty of applications detailed in this chapter. Moreover, optimizations of experimental conditions are also discussed and highlight the versatility and easy-to-use characteristics of G-quadruplexes DNA. Also, synthetic G-quartets, mainly TASQ (for *template-assembled synthetic G-quartets*), developed by chemists showed their ability to mimic G-quadruplexes, thanks to the presence of a G-quartet. Thus, syn‐ thetic G-quartets proved their capability to catalyze peroxidase-mimicking reactions, and these new exciting nature-mimicking catalytic systems are presented in detail in this chapter.

**Keywords:** DNAzyme, G-quadruplex, hemin, G-quartet, TASQ
