Search

The substrate properties of four carbocyclic D and L nucleoside 5'-triphosphate analogs toward HIV and AMV reverse transcriptases and terminal deoxynucleotidyl transferase were evaluated. The compounds of the D-beta and L-beta series were found to be terminating substrates for these enzymes, while the derivatives of the D-alpha and L-alpha series were recognized only by terminal deoxynucleotidyl transferase, suggesting that for the template-independent enzyme the mutual orientation of the two fragments is of no significance. A hypothesis for binding of nucleotides to the DNA polymerase active center was proposed.

2′-3′-Dideoxy-2′,3′-dehydrothymidine 5′-triphosphate (dddTTP) shows termination substrate properties in the DNA synthesis catalyzed by E. coli DNA polymerase I KF, rat liver DNA polymerase β, reverse transcriptases of avian myeloblastosis virus and Raus sarcoma virus and calf thymus terminal deoxynucleotidyl transferase. This implies that the mononucleotide residue of dddTTP incorporates into 3′-termini of newly synthesized DNA chains. However, dddTTP has no influence on the DNA synthesis catalyzed by calf thymus DNA polymerase α. In the case of some DNA polymerases dddTTP was one order of magnitude more effective in comparison with the other known termination substrates.