SYNTHESIS AND PROPERTIES OF ADENOSINE OLIGONUCLEOTIDE ANALOGS CONTAINING METHYLENE GROUPS IN-PLACE OF PHOSPHODIESTER 5'-OXYGENS

The ADP analogue in which the 5'-oxygen has been replaced by a methyle ne group can be prepared by condensing 5'-deoxy-5'-phosphonomethyladen osine with inorganic phosphate. This analogue readily polymerizes onto the primer A-A in the presence of the enzyme polynucleotide phosphory lase and either Mg2+ or Mn2+. The initial products are of the form A-A (-cA)n-cA (where ''-'' and ''-c'' stand for the normal phosphodiester linkage and the linkage in which the 5'-oxygen is replaced with the me thylene group, respectively). Treatment of these with alkali yields ad enosine 2'(3')-phosphate and the series (A(-cA)n-cA containing only ph osphonomethylene linkages. The decamer A(-cA)8-cA interacts with two m olecules of U(-U)8-U to form a triple-standard structure that has a st ability similar to that exhibited by the analogous complex formed from A(-A)8-A and U(-U)8-U. This property, along with the resistance of th ese oligomer analogues toward nucleases that cleave phosphodiester lin kages between the phosphorus and the 5'-oxygen, should provide a stron g rationale for application of phosphonomethylene linkages in schemes for therapeutic drug design that use the antisense strategy.