Nucleobase modification

Oxidative nucleobase modifications leading to strand scission 98CRV1109. 

Upon photo-excitation Ru(II) complexes have been reported to induce three main kinds of reactions of DNA strand cleavage, nucleobase modification, which leads to strand breaks on subsequent treatment with base, and photoadduct formation. 

Burrows CJ, Muller JG (1998) Oxidative nucleobase modifications leading to strand scission. Chem Rev 98 1109-1151... 

Various nucleobase modifications have been used to enhance functional groups available for catalytic aptamers, and imidazole has often been used as a general acid-base catalyst. Deoxyribozymes with RNA cleaving ability have been evolved in the presence of ions incorporating a C5-amino modified dT analogue and the imidazole-modified dA derivative (148). The aptamers showed activity in the presence of Pb(II) ions, and (148) is essential for... 

PNA may be systematically modified to incorporate varied functionality. The two distinct portions of PNA, nucleobase and backbone, can both accommodate alterations. Nucleobase modifications affect a PNA s ability to bind DNA in a sequence-specific manner. A pseudoisocytosine nucleobase has been successfully incorporated in PNAs designed to bind DNA as a triple helix [31]. This nucleobase mimics a protonated cytosine and effectively binds DNA in the Hoogsteen mode. 

PNA is readily labeled for use in a variety of molecular biology applications. The versatile chemistry of PNA has also allowed the preparation of PNA-peptide conjugates and PNA-DNA chimeras. The PNA base unit itself has incorporated backbone and nucleobase modifications to affect solubility and binding characteristics. The application of solid-phase synthesis methods to the preparation of PNA provides researchers with an impressive new molecular biology tool. 

Non-Nucleobase Modifications - Altered Phosphodiester and Sugar Portions... 

The synthesis and characterization of dirhodium tetraacetate in the 1960s introduced a new era for metal-metal bonded compounds due to their diverse array of applications as catalysts [37-39], photocatalysts [40 -43], peptide-modifying agents and metallopeptide catalysts [44-51], DNA and RNA nucleobase-modification catalysts [52], metallo-pharmaceuticals [53-56], photodynamic therapy agents [57], building blocks for the design of supramolecular architectures [58], and others. In this respect, many new Rh2(II,II) systems displaying unique properties have been reported in recent years. 

Nucleobase Modifications In the search for new therapeutic derivatives, substituted triazole rings have been introduced on both pyrimidines [2] and purine nucleosides [3-5] (Figure 10.1). Among all the synthesized compounds, some... 

---