POLYNUCLEOTIDES .7. SYNTHESIS OF RIBOPOLYNUCLEOTIDES CONTAINING 8-SUBSTITUTED PURINE NUCLEOTIDES BY POLYNUCLEOTIDE PHOSPHORYLASE

Polymerization of 8-substituted purine ribonucleoside diphosphates, such as 8-bromoadenosine diphosphate, 8-oxyadenosine diphosphate, 8- bromoguanosine diphosphate, 8-oxyguanosine diphosphate, and8-dimethylaminoguanosine diphosphate, catalyzed by polynucleotide phosphorylase was studied. Although homopolymerization of these diphosphate analogs failed, copolynucleotides were obtainedfrom these analogs and adenosine diphosphate or guanosine diphosphate. The rate and extent of the polymerization decreased according to the amount of analog diphosphates used in the polymerization reaction.Polynucleotides containing 8-substituted purine in either polyadenylic acid or polyguanylic acid chains had lower Tm’s relative to the parent polyadenylic acid or polyguanylic acid, respectively. Melting temperature of the complex of the copolymer, (poly A,BrG)-(poly U)2, was also lower than that of (poly A)-(poly U)2 complex due presumably tothe looping out of nucleotide analog residues. © 1969, American Chemical Society. All rights reserved.