Probing structural factors stabilizing antisense oligonucleotide duplexes : NMR studies of a DNA-DNA duplex containing a formacetal linkage

The duplex formed by annealing the formacetal backbone modified dodecamer d-(CGCGTT OCH2O TTGCGC) to its complementary strand, d(GCGCAAAACGCG) (duplex I), has been studied by NMR techniques and analyzed with reference to its unmodified counterpart (duplex II). Comparison of parameters such as 2D cross-peak intensities, coupling constants, and spectral patterns indicates that structural perturbations caused by the incorporation of the formacetal linkage are minimal and localized to the central T 4 .A 4 block