title: Combined enzymatic and chemical approaches to the synthesis of unique polyribonucleotides.
abstract: The enzymatic polymerization by polynucleotide phosphorylase of 6-chloro-9-(beta-D-ribofuranosyl)purine 5'-diphosphate to poly(6-chloropurinylic acid) and its conversion to poly(6-thioninosinic acid) is described. The sulfur isostere of poly(I) was found not to form a complex with poly(C), but to form a self-association complex with a Tm around 295 degrees K. The sedimentation velocities,  pKa and Tm values of the polymer have been examined under various conditions. A two (or more) stranded helical array is suggested as the most probable structure. Thermal loss of the thione chromophore was noted for poly- (S6I), S6IMP and S6I; the degradation product from S6I was shown to be inosine.
mesh_terms: D000469:Alkaline Phosphatase; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D009994:Osmolar Concentration; D010727:Phosphoric Diester Hydrolases; D011117:Polyribonucleotide Nucleotidyltransferase; D011131:Polyribonucleotides / Q000096:biosynthesis* / Q000138:chemical synthesis; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature
chemical_list: D011131:Polyribonucleotides; D011117:Polyribonucleotide Nucleotidyltransferase; D000469:Alkaline Phosphatase; D010727:Phosphoric Diester Hydrolases