ACYCLIC OLIGONUCLEOTIDE ANALOGS

Acyclic analogues of oligothymidylate and oligoadenylate and their alt ernating copolymers were synthesized to study their thermal melting, t heir stability against snake venom phosphodiesterase and their primer/ template properties using the Klenow fragment of the Escherichia coli DNA polymerase enzyme. Acyclic dodecaadenylate (GlyA)(12) hybridized t o dodecathymidylate p(dT)(12), and the complex presented a sharp melti ng with a T-m at 24 degrees C. This association was confirmed by circu lar dichroism curves which were similar to those of the natural oligon ucleotide duplexes in A-conformation. (GlyA)(12) proved very stable ag ainst snake venom phosphodiesterase hydrolysis. The reaction rate was more than 10 000 times slower than that of p(dT)(12). (GlyA)(12) serve d as a primer for the Klenow DNA polymerase. When (GlyA)(12) was compl exed with the poly(dT) template, the enzyme polymerized dATP but the r eaction was m uch slower than with the (GlyT)(12) primer. Molecular mo delling of atactic (GlyA)(12).(dT)(12) of the A-conformation indicates that this conformation is energetically possible.