BIOPHYSICAL THEORY AND MODELING |
A Quantitative Model of Thermal Stabilization and Destabilization of Proteins by Ligands
Piotras Cimmperman 1, Lina Baranauskiene 1, Simona Jachimoviciute 2, Jelena Jachno 1, Jolanta Torresan 1, Vilma Michailoviene 1, Jurgita Matuliene 1, Jolanta Sereikaite 3, Vladas Bumelis 2 and Daumantas Matulis 1*
1 Institute of Biotechnology
2 Vilnius Gediminas Technical University
3 Vilnius Gedimanas Technical University
* To whom correspondence should be addressed. E-mail: matulis{at}ibt.lt.
Submitted on April 9, 2008
Revised on May 24, 2008
Accepted on 13 June 2008
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Abstract |
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Equilibrium binding ligands usually increase protein thermal stability by an amount proportional to the concentration and affinity of the ligand. High-throughput screening for the discovery of drug-like compounds uses an assay based on thermal stabilization. The mathematical description of this stabilization is well-developed, and the method is widely applicable to the characterization of ligand-protein binding equilibrium. However, numerous cases have been experimentally observed where equilibrium binding ligands destabilize proteins, i.e., diminish protein melting temperature by an amount proportional to the concentration and affinity of the ligand. Here, we present a thermodynamic model that describes ligand binding to various protein states explaining the combined stabilization and destabilization effects. The model also explains non-saturation and saturation effects on the protein melting temperature when the ligand concentration significantly exceeds the protein concentration. Several examples of the applicability of the model are presented, including specific sulfonamide binding to recombinant human carbonic anhydrase II, peptide and ANS binding to the polo box domain of Plk1, and zinc ion binding to the recombinant porcine growth hormone. The same ligands may stabilize and destabilize different proteins, and the same proteins may be stabilized and destabilized by different ligands.
Key Words:
Carbonic anhydrase, Growth hormone, Polo-like kinase, Thermal denaturation, Thermal shift assay, ThermoFluor
