Preparation of stereoregulated antisense oligodeoxyribonucleoside phosphorothioate and interaction with its complementary DNA and RNA.

Diastereoisomeric specificity of oligodeoxyribonucleoside phosphorothioate (OPT) in DNA/OPT and RNA/OPT hybrid formation was investigated. The difference in the configuration between RRRR and SSSS was reflected in the conformation and the stability of the DNA/OPT and RNA/OPT hybrids. Therefore, findings of this report rationalize the antisense effect by non-stereoregulated OPT and the difference of diastereoisomerism in susceptibility to RNase H.