[Ability of 3'-substituted nucleoside phosphothioates to terminate DNA synthesis catalyzed by various...

Ability of some new substrates containing the 5'-alpha-thiotriphosphate residue to terminate the DNA synthesis catalyzed by several DNA polymerases has been investigated. The cell-free test system contained the M13mp10 phage single-stranded DNA and a synthetic oligonucleotide primer. Reverse transcriptase from avian myeloblastosis virus catalyzed termination of DNA synthesis by 3'-azido-3'-fluoro- and 3'-amino-2',3'-dideoxythymidine-5'-(alpha-thio)triphosphates, whereas rat liver DNA polymerase beta and E. coli DNA polymerase I (Klenow's fragment) utilized only the second and the third compounds, and calf thymus DNA polymerase alpha failed to utilize any of the substrates. Low specificity of reverse transcriptase to different moieties of the substrate molecules is discussed.