Polyribonucleotides containing thiopurines: synthesis and properties of poly (6-thioguanylic acid).

The synthesis of poly(2-amino-6-chloropurinylic acid) [poly(n2cl6Pu)] by the polynucleotide phosphorylase catalyzed polymerization of 2-amino-6-chloro-9-(beta-D-ribofuranosyl)purine 5'-diphosphate and its chemical conversion to poly(6-thioguanylic acid) [poly(s6G)] is described. Poly(s6G) was found to form a relatively unstable complex with poly(C), the properties of which were incompatible with those previously reported for the same complex prepared by another method [Darlix, J.L., Fromageot, P., and Reich, E. (1973), Biochemistry 12, 914]. It was found that poly(s6G) could be thermally converted to a copolymer of which with poly(C) was strikingly similar to that reported earlier for poly(s6G)-poly(C).