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Intrinsic thermodynamics of inhibitor binding to human carbonic anhydrase IX

Vaida Linkuvienė1, Jurgita Matulienė1, Vaida Juozapaitienė1

  • 1Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Vilnius University, Graičiūno 8, Vilnius LT-02241, Lithuania.

Biochimica Et Biophysica Acta
|January 23, 2016
PubMed
Abstract

Insights

This study quantifies the binding thermodynamics of carbonic anhydrase 9th isoform (CA IX) inhibitors. Differentiating intrinsic from observed binding parameters is crucial for developing effective anticancer drugs targeting CA IX.

Area of Science:

  • Biochemistry
  • Chemical Biology
  • Pharmacology

Background:

  • Human carbonic anhydrase 9th isoform (CA IX) is a key cancer marker and therapeutic target.
  • Aromatic sulfonamide compounds are investigated as CA IX inhibitors.
  • Sulfonamide binding involves linked reactions affecting thermodynamic parameters.

Purpose of the Study:

  • To determine the intrinsic thermodynamic parameters of CA IX inhibitor binding.
  • To establish structure-thermodynamics relationships for CA IX inhibitors.
  • To differentiate observed from intrinsic binding parameters for drug development.

Main Methods:

  • Fluorescent thermal shift assay to measure binding affinities (observed and intrinsic).
  • Isothermal titration calorimetry to determine binding enthalpies and entropies.
  • Determination of CA IX pKa and hydroxide protonation enthalpy.

Main Results:

  • CA IX pKa determined as 6.8; hydroxide protonation enthalpy as -24 kJ/mol.
  • Intrinsic affinities down to 0.01 nM and observed affinities of 2 nM were measured.
  • Analysis enabled the correlation of compound structure with binding thermodynamics.

Conclusions:

  • Intrinsic thermodynamic parameters are key for understanding CA IX inhibitor interactions.
  • Distinguishing intrinsic from observed parameters is vital for drug candidate development.
  • This work facilitates the design of novel CA IX-targeting anticancer agents.
Keywords:
Benzenesulfonamide inhibitorsCarbonic anhydraseDrug designFluorescent thermal shift assayIntrinsic thermodynamics of protein-ligand bindingIsothermal titration calorimetry

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