Backbone modification - Chemistry

Phosphorothioate analogs in which a non-bridging oxygen has been replaced by sulfur have widespread use in molecular biology. The increased resistance of phosphorothioates against nuclease digestion has prompted the consideration of these molecules for medical purposes. In addition to their value as antisense probes, phosphorothioates have also been used for the site specific attachment of reporter groups at the DNA/RNA backbone and for preventing degradation of oligonucleotides by 3'→'5'-exonuclease activities of proof reading DNA polymerases such as Vent and Pfu. Phosphorothioate-substituted RNA has been used to study specific RNA-Protein interactions.