[en] The 1,2,4-benzothiadiazine 1,1-dioxide type of positive allosteric modulators of the ionotropic glutamate receptor A2 (GluA2) are promising lead compounds for the treatment of cognitive disorders, e.g., Alzheimer’s disease. The modulators bind in a cleft formed by the interface of two neighboring ligand binding domains and act by stabilizing the agonist-bound open- channel conformation. The driving forces behind the binding of these modulators can be significantly altered with only minor substitutions to the parent molecules. In this study, we show that changing the 7-fluorine substituent of modulators BPAM97 (2) and BPAM344 (3) into a hydroxyl group (BPAM557 (4) and BPAM521 (5), respectively), leads to a more favorable binding enthalpy (DH, kcal/mol) from 4.9 (2) and 7.5 (3) to 6.2 (4) and 14.5 (5), but also a less favorable binding entropy ( TDS, kcal/mol) from 2.3 (2) and 1.3 (3) to 0.5 (4) and 4.8 (5). Thus, the dissociation constants (Kd, mM) of 4 (11.2) and 5 (0.16) are similar to those of 2 (5.6) and 3 (0.35). Functionally, 4 and 5 potentiated responses of 10 mM L-glutamate at homomeric rat GluA2(Q)i receptors with EC50 values of 67.3 and 2.45 mM, respectively. The binding mode of 5 was examined with x-ray crystallography, showing that the only change compared to that of earlier compounds was the orientation of Ser-497 pointing toward the hydroxyl group of 5. The favorable enthalpy can be explained by the formation of a hydrogen bond from the side-chain hydroxyl group of Ser-497 to the hydroxyl group of 5, whereas the unfavorable entropy might be due to desolva- tion effects combined with a conformational restriction of Ser-497 and 5. In summary, this study shows a remarkable example of enthalpy-entropy compensation in drug development accompanied with a likely explanation of the underlying structural mechanism.
Research Center/Unit :
Centre Interfacultaire de Recherche du Médicament - CIRM
Disciplines :
Pharmacy, pharmacology & toxicology
Author, co-author :
Krintel, Christian ✱; Københavns Universitet - KU > Dpt of Drug Design and Pharmacology
Francotte, Pierre ✱; Université de Liège > Département de pharmacie > Chimie pharmaceutique
Pickering, Darryl S.; Københavns Universitet - KU
Juknaite, Lina; Københavns Universitet - KU
Pøhlsgaard, Jacob; Københavns Universitet - KU
Olsen, Lars; Københavns Universitet - KU
Frydenvang, Karla; Københavns Universitet - KU
Goffin, Eric ; Université de Liège > Département de pharmacie > Chimie pharmaceutique
Pirotte, Bernard ; Université de Liège > Département de pharmacie > Chimie pharmaceutique
Kastrup, Jette; Københavns Universitet - KU
✱ These authors have contributed equally to this work.
Language :
English
Title :
Enthalpy-Entropy Compensation in the Binding of Modulators at Ionotropic Glutamate Receptor GluA2
Publication date :
07 June 2016
Journal title :
Biophysical Journal
ISSN :
0006-3495
eISSN :
1542-0086
Publisher :
Biophysical Society, Bethesda, United States - Maryland
S.F. Traynelis, and L.P. Wollmuth R. Dingledine Glutamate receptor ion channels: structure, regulation, and function Pharmacol. Rev. 62 2010 405 496
A.I. Sobolevsky, M.P. Rosconi, and E. Gouaux X-ray structure, symmetry and mechanism of an AMPA-subtype glutamate receptor Nature 462 2009 745 756
N. Armstrong, and E. Gouaux Mechanisms for activation and antagonism of an AMPA-sensitive glutamate receptor: crystal structures of the GluR2 ligand binding core Neuron 28 2000 165 181
Y. Sun, and R. Olson E. Gouaux Mechanism of glutamate receptor desensitization Nature 417 2002 245 253
R. Jin, and S. Clark K.M. Partin Mechanism of positive allosteric modulators acting on AMPA receptors J. Neurosci. 25 2005 9027 9036
Y. Stern-Bach, and S. Russo C. Rosenmund A point mutation in the glutamate binding site blocks desensitization of AMPA receptors Neuron 21 1998 907 918
C. Krintel, and K. Frydenvang J.S. Kastrup Thermodynamics and structural analysis of positive allosteric modulation of the ionotropic glutamate receptor GluA2 Biochem. J. 441 2012 173 178
P. Francotte, and Pd. Tullio B. Pirotte Design, synthesis, and pharmacology of novel 7-substituted 3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxides as positive allosteric modulators of AMPA receptors J. Med. Chem. 50 2007 3153 3157
K.A. Yamada, and S.M. Rothman Diazoxide blocks glutamate desensitization and prolongs excitatory postsynaptic currents in rat hippocampal neurons J. Physiol. 458 1992 409 423
K.A. Yamada, and C.M. Tang Benzothiadiazides inhibit rapid glutamate receptor desensitization and enhance glutamatergic synaptic currents J. Neurosci. 13 1993 3904 3915
C.P. Ptak, A.H. Ahmed, and R.E. Oswald Probing the allosteric modulator binding site of GluR2 with thiazide derivatives Biochemistry 48 2009 8594 8602
A.B. Nørholm, and P. Francotte J.S. Kastrup Synthesis, pharmacological and structural characterization, and thermodynamic aspects of GluA2-positive allosteric modulators with a 3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide scaffold J. Med. Chem. 56 2013 8736 8745
P. Francotte, and A.B. Nørholm B. Pirotte Positive allosteric modulators of 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid receptors belonging to 4-cyclopropyl-3,4-dihydro-2h-1,2,4-pyridothiadiazine dioxides and diversely chloro-substituted 4-cyclopropyl-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxides J. Med. Chem. 57 2014 9539 9553
Y. Girard, J.G. Atkinson, and J. Rokach A new synthesis of 1,2,4-benzothiadiazines and a selective preparation of o-aminobenzenesulfonamides J. Chem. Soc., Perkin Trans. 1 1979 1043 1047
T. Ursby, and J. Unge M.M. Thunnissen The macromolecular crystallography beamline I911-3 at the MAX IV laboratory J. Synchrotron Radiat. 20 2013 648 653
T.G. Battye, and L. Kontogiannis A.G. Leslie iMOSFLM: a new graphical interface for diffraction-image processing with MOSFLM Acta Crystallogr. D Biol. Crystallogr. 67 2011 271 281
Collaborative Computational Project, Number 4 The CCP4 suite: programs for protein crystallography Acta Crystallogr. D Biol. Crystallogr. 50 1994 760 763
A.J. McCoy, and R.W. Grosse-Kunstleve R.J. Read Phaser crystallographic software J. Appl. Cryst. 40 2007 658 674
P. Emsley, and B. Lohkamp K. Cowtan Features and development of Coot Acta Crystallogr. D Biol. Crystallogr. 66 2010 486 501
P.D. Adams, and P.V. Afonine P.H. Zwart PHENIX: a comprehensive Python-based system for macromolecular structure solution Acta Crystallogr. Sect. D: Biol. Crystallogr. 66 2010 213 221
S. Hayward, and H.J. Berendsen Systematic analysis of domain motions in proteins from conformational change: new results on citrate synthase and T4 lysozyme Proteins 30 1998 144 154
A.V. Marenich, and R.M. Olson D.G. Truhlar Self-consistent reaction field model for aqueous and nonaqueous solutions based on accurate polarized partial charges J. Chem. Theory Comput. 3 2007 2011 2033
C.P. Ptak, and C.L. Hsieh R.E. Oswald Role of stoichiometry in the dimer-stabilizing effect of AMPA receptor allosteric modulators ACS Chem. Biol. 9 2014 128 133
A.P. Larsen, and P. Francotte J.S. Kastrup Synthesis and pharmacology of mono-, di- and trialkyl-substituted 7-chloro-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxides combined with X-ray structure analysis to understand the unexpected structure-activity relationship at AMPA receptors ACS Chem. Neurosci. 7 2016 378 390
A. Biela, and M. Betz G. Klebe Water makes the difference: rearrangement of water solvation layer triggers non-additivity of functional group contributions in protein-ligand binding ChemMedChem 7 2012 1423 1434
R.A. Laskowski, and M.W. MacArthur J.M. Thornton PROCHECK: a program to check the stereochemical quality of protein structures J. Appl. Cryst. 26 1993 283 291
A.B. Nørholm, and P. Francotte C. Oostenbrink Thermodynamic characterization of new positive allosteric modulators binding to the glutamate receptor A2 ligand-binding domain: combining experimental and computational methods unravels differences in driving forces J. Chem. Inf. Model. 54 2014 3404 3416