The development of nucleoside phosphorothioates is described in its histori
cal context. Examples of the interaction of phosphorothioate groups, presen
t either in oligodeoxynucleotides or in DNA, with nucleases are presented.
The structural features responsible for the resistance of the phosphorothio
ates toward degradation by nucleases are discussed, as are the possible rea
sons for the high-affinity interaction of phosphorothioate oligodeoxynucleo
tides with certain proteins.