Abstract
Stability of oligo(nucleoside phosphorothioate)s (PS-oligos) in HUVEC (human umbilical vein endothelial cells) has been studied. Cytosolic fraction of HUVEC possesses 3′-exonucleolytic activity which is responsible for degradation of natural oligomers and PS-oligos. The enzyme is Rp-specific, i.e. it cleaves internucleotide phosphorothioate function of Rp- and not Sp-configuration at phosphorus atom.