Additional level of information about complex interaction between non-nucleoside inhibitor and HIV-1 reverse...

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• Mutations in HIV-1 reverse transcriptase (K103N, Y181C) can confer resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs).
• Understanding the thermodynamic basis of drug-enzyme interactions is crucial for developing effective HIV therapies.

Purpose of the Study:

• To elucidate the thermodynamic characteristics of the interaction between mutant HIV-1 reverse transcriptase (K103N and Y181C) and the NNRTI MIV-150.
• To investigate the structural rearrangements and energetic contributions governing inhibitor binding.

Main Methods:

• Thermodynamic analysis by determining the temperature dependence of kinetic rate constants.
• Characterization of enzyme conformational changes and inhibitor binding energetics.

Main Results:

• Significant entropic changes were observed during enzyme isomerization and inhibitor binding, indicating major structural rearrangements.
• The overall inhibitor binding equilibrium was predominantly enthalpy-driven.
• High- and low-affinity interactions exhibited distinct thermodynamic profiles, with higher affinity showing a greater enthalpic component.
• Thermodynamic profiles differed significantly between the two enzyme variants (K103N and Y181C).

Conclusions:

• The interaction between mutant HIV-1 reverse transcriptase and MIV-150 involves substantial structural dynamics.
• Enthalpy plays a dominant role in driving inhibitor binding equilibrium, despite significant entropic contributions.
• Thermodynamic profiling provides insights into enzyme-inhibitor interactions not evident from single-temperature kinetics.