DNA Conjugation by the Staudinger Ligation : New Thymidine Analogues

Two novel modified 2′-deoxyuridine triphosphates carrying an azide functionality linked to the nucleobase were synthesized. For probing the sterical influence on enzymatic incorporation and Staudinger ligation, differently sized flexible linkers were chosen. Both nucleotides can completely replace natural thymidine in primer extension as well as polymerase chain reaction (PCR) using Pyrococcus woesei DNA polymerase. For PCR with larger gene fragments as template, however, the longer linker disturbs the DNA polymerase and yields less product. For azide-labeled primer extension products, subsequent conjugation of suitably functionalized phosphines via Staudinger ligation was achieved, for example for the conjugation of biotin as an affinity tag.publishe