ENZYMATIC AND HYBRIDIZATION PROPERTIES OF OLIGONUCLEOTIDE ANALOGS CONTAINING NOVEL PHOSPHOTRIESTER INTERNUCLEOTIDE LINKAGE

Enhanced cellular uptake, stable and discriminating hybridization and increased stability in biological media are of particular interest for oligonucleotides of potential therapeutic application. Additionally, toxicity or immunogenicity of the oligonucleotide analogues and their biodegradation products should be minimized by minimal alteration of t he biological structure and effort and cost of bulk production should be as low as possible by using a standard automated synthesis protocol . Oligonucleotide phosphotriesters with oligoethyleneglycol substituen ts show promise to ideally combine all these advantages. Here we descr ibe the hybridization properties and the stability of modified oligonu cleotides containing triester internucleotide linkages substituted wit h alpha,omega-dihydroxy-(3,6-dioxa)-octan-1-yl group (''triethylenegly col triester linkages'') towards enzymatic degradation. The triester l inkages are stable towards exo- and endonucleases. Regardless of numbe r and position of triester linkages, the modified oligonucleotides sho wed practically no decrease of T-m in hybridization studies with compl ementary biological oligonucleotides. In further enzymatic studies the modified oligonucleotides were highly stable towards nucleases in hum an blood serum.