Polymerase-mediated high-density incorporation of amphiphilic functionalities into DNA: enhancement of nuclease resistance and stability in human serum.

Abstract Modified oligodeoxyribonucleotides (mdODNs) bearing multiple copies of an amphiphilic functional group were enzymatically synthesized by simultaneous incorporation of base-modified 5′-triphosphate analogs of 2′-deoxyguanosine (dG am TP), 2′-deoxyuridine (dU am TP), 2′-deoxyadenosine (dA am TP), and 2′-deoxycytosine (dC am TP). The amphiphilic functionality, that is, ( E )-38,53-dioxo-2,5,8,11,14,17,20,23,26,29,32,35-dodecaoxa-39,52-diazapentapentacont-54-en-55-yl group, consists of the water soluble dodeca(ethylene glycol) chain and the hydrophobic dodecyl chain. An enzymatically synthesized ODN, composed of a 20-mer 5′-terminal segment containing 2′- O ,4′-C-methylene-bridged/linked bicyclic ribonucleotide (B/L nucleotide) and a 12-mer 3′-terminal segment containing the nucleobase-modified analogs, exhibits very high resistance against phosphodiesterase I and is stable in human serum for a longer period when compared with ODN, where the 12-mer 3′-terminal segment contains unmodified nucleotides.