INHIBITORY EFFECTS OF TRIPHOSPHATE DERIVATIVES OF OXETANOCIN-G AND RELATED-COMPOUNDS ON EUKARYOTIC AND VIRAL-DNA POLYMERASES AND HUMAN-IMMUNODEFICIENCY-VIRUS REVERSE-TRANSCRIPTASE

In order to clarify the biological activities of (-)-oxetanocin G, and (-)-oxetanocin A and its carbocyclic analogue, (-)-carboxetanocin G, the inhibitory effects of triphosphate derivatives of these compounds (OXT-GTP, OXT-ATP, and C-OXT-GTP) on eukaryotic and viral DNA polymerases were examined. DNA polymerase-alpha purified from calf thymus was weakly inhibited by OXT-GTP and OXT-ATP but strongly by C-OXT-GTP, the K(i) value being 0.22-mu-M. On the other hand, rat DNA polymerase-beta was not affected by these analogues. DNA polymerase-gamma purified from bovine testes was very weakly inhibited by OXT-GTP and OXT-ATP, but not by C-OXT-GTP. DNA polymerase from herpes simplex virus type-II (HSV-II) was strongly inhibited by all three analogues, the K(i) values ranging from 0.5 to 1.0-mu-M. Human immunodeficiency virus-encoded reverse transcriptase (HIV RT) was also strongly inhibited by these three analogues, the K(i) value of C-OXT-GTP being slightly smaller than that of OXT-GTP or OXT-ATP. Analysis of products synthesized on singly primed M13 single-stranded DNA by DNA polymerase-alpha, HSV-II DNA polymerase or HIV RT in the presence of the analogues revealed that OXT-GTP and C-OXT-GTP were incorporated into DNA and caused chain termination mainly at sites one or two nucleotides beyond the cytosine bases on the template.