DNA Analogues with Nonphosphodiester Backbones

This review discusses the recent developments of DNA analogues with nonphosphodiester backbones in terms of DNA structure and antisense and antigene potential. A larger number of derivatives are now available in which the phosphodiester linkage has been replaced but the deoxyribose retained. However, only a few of these (e.g. the ones having a thioformacetal or a carboxamide linkage) appear to be good structural DNA mimics. Two successful attempts to replace the entire deoxyribose phosphate backbone have been reported, the morpholino derivatives and the peptide nucleic acids (PNA), which contain an N-(2-aminoethyl)glycine-based pseudopeptide backbone. Most information is available on the PNA, which is a very promising DNA mimic. In conclusion, the deoxyribose phosphate backbone is not essential for a potent structural DNA mimic and not even required for a helical duplex structure.