This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.108.134973v1 95/7/3222    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Cimmperman, P. Articles by Matulis, D. PubMed PubMed Citation Articles by Cimmperman, P. Articles by Matulis, D.

A Quantitative Model of Thermal Stabilization and Destabilization of Proteins by Ligands

Piotras Cimmperman ^*, Lina Baranauskien ^*, Simona Jachimoviit , Jelena Jachno ^*, Jolanta Torresan ^*, Vilma Michailovien ^*, Jurgita Matulien ^*, Jolanta Sereikait , Vladas Bumelis  and Daumantas Matulis ^*

^* Laboratory of Biothermodynamics and Drug Design, Institute of Biotechnology, LT-02241 Vilnius, Lithuania; and Department of Chemistry and Bioengineering, Faculty of Fundamental Sciences, Vilnius Gediminas Technical University, LT-10223 Vilnius, Lithuania

Correspondence: Address reprint requests to Daumantas Matulis, E-mail: matulis{at}ibt.lt.

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 the native and unfolded (denatured) protein states explaining the combined stabilization and destabilization effects. The model also explains nonsaturation 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 hCAII, 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.