Kinetic and Thermodynamic Evaluation of Kynurenic Acid Binding to GluR1270-300 Polypeptide by Surface Plasmon Resonance Experiments

Ádám Juhász, Edit Csapó, Ditta Ungor, G. Tóth, L. Vécsei, I. Dékány

Research output: Article

12 Citations (Scopus)

Abstract

This work clearly demonstrates an evaluation process that is easily performed and is simply based on the fitting of temperature-dependent surface plasmon resonance (SPR) sensorgrams to provide detailed thermodynamic characterization of biologically relevant interactions. The reversible binding of kynurenic acid (KYNA) on human glutamate receptor (GluR1) polypeptide (GluR1270-300)-modified gold surface has been studied at various temperatures under physiological conditions by two-dimensional SPR experiments. The registered sensorgrams were fitted by using different kinetic models without application of any commercial software. Assuming that the association of GluR1270-300-KYNA complex is first order in both reactants, the association (ka) and dissociation (kd) constants as well as the equilibrium constants (KA) and the Gibbs free-energy change (ΔG°) were given at 10, 20, 30, and 40 °C. Moreover, the enthalpy (ΔH° = -27.91 kJ mol-1), entropy (ΔS° = -60.33 J mol-1 K-1), and heat capacity changes (ΔCp = -1.28 kJ mol-1 K-1) of the model receptor-ligand system were also calculated using a spreadsheet program. Negative values of ΔG° and ΔH° indicate the exothermic formation of a stable GluR1270-300-KYNA complex, because the |ΔH| > |TΔS| relation suggests an enthalpy-driven binding process. The negative ΔH° and ΔS° values strongly support the formation of a salt bridge between KYNA and the positively charged residues of the polypeptide (Arg, Lys) at pH 7.4, confirmed by molecular docking calculations as well.

Original languageEnglish
Pages (from-to)7844-7850
Number of pages7
JournalJournal of Physical Chemistry B
Volume120
Issue number32
DOIs
Publication statusPublished - aug. 18 2016

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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