Peptide nucleic acids: Analogs and derivatives

Peptide Nucleic Acids (PNA) invented ten years ago are emerging rapidly as useful molecules in DNA hybridization and antisense techniques. Although th erapeutic drugs based on PNA are still not in sight, applications in diagno stics, in particular in situ hybridization and PCR based systems, are makin g rapid strides. The simple structure of PNA in combination with impressive DNA mimicking properties has already provided inspiration to many syntheti c organic chemists for designing and preparing several derivatives and anal ogs towards improving their physico-chemical and biological properties. Thi s review which is not intended to be exhaustive, is aimed at highlighting t he current progress in the areas of PNA chemistry, structure, hybridization , and applications. The various chemical backbone modifications of PNA repo rted till date are summarized in the context of DNA hybridization propertie s.