Kinetic studies with the non-nucleoside HIV-1 reverse transcriptase inhibitor U-88204E

Abstract

The bis(heteroaryl)piperazine U-88204E is a potent inhibitor of HIV-1 reverse transcriptase (RT) and possesses excellent anti-HIV activity in HIV-1-infected lymphocytes grown in tissue culture. Enzymatic kinetic studies of the RNA- and DNA-dependent DNA polymerases of RT were carried out in order to determine whether the inhibitor interacts directly with the template:primer or deoxyribonucleotide triphosphate (dNTP) binding sites of the polymerase. The experimental results were analyzed using steady-state or Briggs-Haldane kinetics, by assuming that the template:primer binds to the enzyme first followed by the dNTP and that the polymerase functions processively. The results of the analysis show that the inhibitor acts as a mixed to noncompetitive inhibitor with respect to both the template:primer and the dNTP binding sites. The potency of U-88204E on the RNA-directed DNA polymerase activity depends on the base composition of the template:primer. The Ki values for the poly(rC):(dG)10-directed reactions were at least 7 times lower than the ones for reactions directed by poly(rA):(dT)10. The inhibitor did not inhibit the RNase H function of HIV-1 RT nor did it impair the RNA-directed DNA polymerase activity of HIV-2 RT. These data thus demonstrate the unique specificity of U-88204E for HIV-1 RT.

Novel Nonnucleoside Inhibitors That Select Nucleoside Inhibitor Resistance Mutations in Human Immunodeficiency Virus Type 1 Reverse Transcriptase

“…The selection of resistant viruses with amino acid changes surrounding the catalytic site initially suggested to us that this series binds to the catalytic site of HIV-1 RT, but this is not supported by the enzyme kinetic data. VRX-413638 was found to be a linear mixed-type inhibitor rather than a competitive inhibitor with respect to its nucleotide substrate, similar to many other NNRTIs (1,12,21). Unlike the other NNRTIs, however, VRX-329747 and VRX-413638 do not select for resistance mutations within the hydrophobic NNRTI pocket, and they retain activity against NNRTI-resistant mutants, suggesting that they do not bind within the NNRTI pocket either.…”

REVIEW : Recent advances in developing web-servers for predicting protein attributes

“…One is to target the HIV (human immunodeficiency virus) reverse transcriptase (see, e.g., [165][166][167][168][169][170][171]); the other is to design HIV protease inhibitors [128,136,138,139,[172][173][174].…”

L-743, 726 (DMP-266): a novel, highly potent nonnucleoside inhibitor of the human immunodeficiency virus type 1 reverse transcriptase

“…The compounds bind to a common site on the RT heterodimer that is distinct from the enzyme's active site (5,8,15,18,20). Kinetically, the NNRTIs' inhibitory activities are generally noncompetitive with respect to the template-primer and nucleotide substrate (1,3,6,9). The compounds appear to function by mediating a noted decrease in the enzyme's polymerizing activity (16).…”