Affinity of reverse transcriptase for some polynucleotide inhibitors.
The relative affinity of avian myeloblastosis virus reverse transcriptase for (U)n and a series of (U)n analogs has been measured directly in solution under conditions previously used to demonstrate the inhibitory properties of these polynucleotides. The affinities were measured by electron spin resonance through a quantitative competition approach where the concentration of each polynucleotide required to compete with the macromolecular spin probe (ls4U,U)n for reverse transcriptase was observed. Using this approach the following relative affinities were determined: K(dUfl)n = 1.6K(dUz)n = 13K(dT)n = 20K(U)320-640 = 57K(dU)n = 167K(U)80 greater than 167K(Um)n These results show that the affinity of (U)n for reverse transcriptase is affected by modifying the (U)n matrix and by the molecular weight of (U)n. In addition, the effect of some factors such as Mg+2 and salt on the polynucleotide affinity for the enzyme was measured. The results show that the same binding, i.e., the fraction of saturation F as a function of the nanomoles of reverse transcriptase added, was observed in the presence or absence of Mg+2, whereas increasing the KCl concentration from 0.04 to 0.5M completely dissociates the polynucleotide X enzyme complex.
D009189:Avian Myeloblastosis Virus / Q000201:enzymology; D001665:Binding Sites; D001667:Binding, Competitive; D004578:Electron Spin Resonance Spectroscopy; D008274:Magnesium / Q000494:pharmacology; D008956:Models, Chemical; D009994:Osmolar Concentration; D011119:Polynucleotides / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism; D018894:Reverse Transcriptase Inhibitors
D011119:Polynucleotides; D018894:Reverse Transcriptase Inhibitors; D012194:RNA-Directed DNA Polymerase; D008274:Magnesium