Photocleavable Biotin Phosphoramidite for 5′-End-Labeling, Affinity Purification and Phosphorylation of Synthetic Oligonucleotides

We report the design, synthesis and evaluation of a non-nucleosidic photocleavable biotin phosphoramidite (PCB-phosphoramidite) which provides a simple method for purification and phosphorylation of oligonucleotides. This reagent introduces a photocleavable biotin label (PCB) on the 5′-terminal phosphate of synthetic oligonucleotides and is fully compatible with automated solid support synthesis. HPLC analysis shows that the PCB moiety is introduced predominantly on full-length sequences and is retained during cleavage of the synthetic oligonucleotide from the solid support and during subsequent deprotection with ammonia. The full-length 5′-PCB-labeled oligonucleotide can then be selectively isolated from the crude oligonucleotide mixture by incubation with immobilized streptavidin. Upon irradiation with 300–350 nm light the 5′-PCB moiety is cleaved with high efficiency in