AUTOMATED SYNTHESIS OF BRANCHED OLIGODEOXYNUCLEOTIDE ANALOGS USING ARABINO-URIDINE AS BRANCHING NUCLEOTIDE

Fully automated synthesis of branched oligodeoxynucleotides (branched ODNs) has been accomplished using 2'-O-levulinyl- or 5'-O-levulinyl-pr otected arabino-uridine derivatives as branching monomers. Selective r emoval of the levulinyl groups is accomplished using 0.5 M hydrazine h ydrate in a pyridine-acetic acid-water (4:3:0,35, v/v/v) buffer. The a ffinity of the branched ODNs towards complementary DNA has been evalua ted at 260 nm and 284 nm during thermal denaturing experiments. Enhanc ed affinity of a branched ODN compared with the corresponding linear r eference is attributed to bimolecular triple helix formation.