Vaida Linkuvienė1, Jurgita Matulienė1, Vaida Juozapaitienė1, Vilma Michailovienė1, Jelena Jachno1, Daumantas Matulis2. 1. Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Vilnius University, Graičiūno 8, Vilnius LT-02241, Lithuania. 2. Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Vilnius University, Graičiūno 8, Vilnius LT-02241, Lithuania. Electronic address: daumantas.matulis@bti.vu.lt.
Abstract
BACKGROUND: Human carbonic anhydrase 9th isoform (CA IX) is an important marker of numerous cancers and is increasingly interesting as a potential anticancer drug target. Various synthetic aromatic sulfonamide-bearing compounds are being designed as potent inhibitors of CA IX. However, sulfonamide compound binding to CA IX is linked to several reactions, the deprotonation of the sulfonamide amino group and the protonation of the CA active site Zn(II)-bound hydroxide. These linked reactions significantly affect the affinities and other thermodynamic parameters such as enthalpies and entropies of binding. METHODS: The observed and intrinsic affinities of compound binding to CA IX were determined by the fluorescent thermal shift assay. The enthalpies and entropies of binding were determined by the isothermal titration calorimetry. RESULTS: The pKa of CA IX was determined to be 6.8 and the enthalpy of CA IX-Zn(II)-bound hydroxide protonation was -24 kJ/mol. These values enabled the analysis of intrinsic thermodynamics of a library of compounds binding to CA IX. The most strongly binding compounds exhibited the intrinsic affinity of 0.01 nM and the observed affinity of 2 nM. CONCLUSIONS: The intrinsic thermodynamic parameters of compound binding to CA IX helped to draw the compound structure to thermodynamics relationship. GENERAL SIGNIFICANCE: It is important to distinguish the intrinsic from observed parameters of any disease target protein interaction with its inhibitors as drug candidates when drawing detailed compound structure to thermodynamics correlations.
BACKGROUND:Human carbonic anhydrase 9th isoform (CA IX) is an important marker of numerous cancers and is increasingly interesting as a potential anticancer drug target. Various synthetic aromatic sulfonamide-bearing compounds are being designed as potent inhibitors of CA IX. However, sulfonamide compound binding to CA IX is linked to several reactions, the deprotonation of the sulfonamide amino group and the protonation of the CA active site Zn(II)-bound hydroxide. These linked reactions significantly affect the affinities and other thermodynamic parameters such as enthalpies and entropies of binding. METHODS: The observed and intrinsic affinities of compound binding to CA IX were determined by the fluorescent thermal shift assay. The enthalpies and entropies of binding were determined by the isothermal titration calorimetry. RESULTS: The pKa of CA IX was determined to be 6.8 and the enthalpy of CA IX-Zn(II)-bound hydroxide protonation was -24 kJ/mol. These values enabled the analysis of intrinsic thermodynamics of a library of compounds binding to CA IX. The most strongly binding compounds exhibited the intrinsic affinity of 0.01 nM and the observed affinity of 2 nM. CONCLUSIONS: The intrinsic thermodynamic parameters of compound binding to CA IX helped to draw the compound structure to thermodynamics relationship. GENERAL SIGNIFICANCE: It is important to distinguish the intrinsic from observed parameters of any disease target protein interaction with its inhibitors as drug candidates when drawing detailed compound structure to thermodynamics correlations.
Authors: Aurelija Mickevičiūtė; David D Timm; Marius Gedgaudas; Vaida Linkuvienė; Zhiwei Chen; Abdul Waheed; Vilma Michailovienė; Asta Zubrienė; Alexey Smirnov; Edita Čapkauskaitė; Lina Baranauskienė; Jelena Jachno; Jurgita Revuckienė; Elena Manakova; Saulius Gražulis; Jurgita Matulienė; Enrico Di Cera; William S Sly; Daumantas Matulis Journal: Eur Biophys J Date: 2017-10-03 Impact factor: 1.733