Synthesis and enzymatic characterization of P1-thio-P2-oxo trideoxynucleoside diphosphates having AZT, FdU, or dT at the 3'-position

Synthesis of stable azide and alkyne functionalized phosphoramidite nucleosides

The use of CuAAC chemistry to crosslink and stabilize oligonucleotides has been limited by the incompatibility of azides with the phosphoramidites used in automated oligonucleotide synthesis. Herein we report optimized reaction conditions to synthesize azide derivatives of thymidine and cytidine phosphoramidites. Investigation of the stability of the novel phosphoramidites using ³¹P NMR at room temperature showed less than 10% degradation after 6 hours. The azide modified thymidine was successfully utilized as an internal modifier in the standard phosphoramidite synthesis of a DNA sequence. The synthesized azide and alkyne derivatives of pyrimidines will allow efficient incorporation of azide and alkyne click pairs into nucleic acids, thus widening the applicability of click chemistry in investigating the chemistry of nucleic acids.

Azide phosphoramidite in direct synthesis of azide-modified oligonucleotides

Azide and phosphoramidite functions were found to be compatible within one molecule and stable for months in solution kept frozen at -20 °C. An azide-carrying phosphoramidite was used for direct introduction of multiple azide modifications into synthetic oligonucleotides. A series of azide-containing oligonucleotides were modified further using click reactions with alkynes.

Synthesis and polymerase chain reaction amplification of DNA strands containing an unnatural triazole linkage

DNA strands containing an unnatural T-triazole-T linkage have been synthesized by click DNA ligation between oligonucleotides with 3'-AZT and 5'-propargylamido dT and amplified efficiently by polymerase chain reaction (PCR) using several different polymerases. DNA sequencing of PCR amplicons and clones in two different sequence contexts revealed the presence of a single thymidine at the ligation site. The remarkable ability of thermostable polymerases to reproducibly copy DNA templates containing such an unnatural backbone opens up intriguing possibilities in gene synthesis, genetic analysis, biology, and nanotechnology.