The effect of phosphonylmethyl analogs of ribonucleoside 5'-diphosphates on (E. coli) polynucleotide phosphorylase catalyzed reactions

Abstract

Ribonucleoside 5'-O-phosphorylphosphonylmethyl ethers (I) are not substrates of Escherichia coli polynucleoside phosphorylase in the presence of either Mg2+- or Mn2+-ions. Compounds I are efficient competitive inhibitors of the polymerization of naturally occurring ribonucleoside 5'-diphosphates (Ki/Km 2 . 10-3 - 10-1). The analogs are not incorporated either into the polymer chain or into its termini during copolymerization with the natural substrate yet the homopolymer obtained shows a larger (by 20-85%) chain length. The presence of short oligonucleotides containing analogs II was not found after the polymerization reaction either. PolyA and polyC phosphorolyses are not affected by the presence of either naturally occurring 5'-diphosphates or of compounds Ib-Id. Adenine analog Ia as the only one significantly stimulates the phosphorolysis reaction catalyzed by E. coli polynucleotide phosphorylase.