Thermodynamics enthalpy-entropy compensation

The relationship of thermodynamic functions of selective bonding of Hb to a series of carboxylic CP in the variation of the degree of ionization of carboxylic groups is expressed by the effect of enthalpy-entropy compensation (Fig. 18). The compensation effect of enthalpy and entropy components is the most wide-spread characteristic of many reactions in aqueous solutions for systems with a cooperative change in structure [78],... 

Guillaume et al. [69] presented a high performance liquid chromatographic method for an association study of miconazole and other imidazole derivatives in surfactant micellar using a hydrophilic reagent, Montanox DF 80. The thermodynamic results obtained showed that imidazole association in the surfactant micelles was effective over a concentration of surfactant equal to 0.4 pM. In addition, an enthalpy-entropy compensation study revealed that the type of interaction between the solute and the RP-18 stationary phase was independent of the molecular structure. The thermodynamic variations observed were considered the result of equilibrium displacement between the solute and free ethanol (respectively free surfactant) and its clusters (respective to micelles) created in the mobile phase. 

It would be somewhat surprising that the enthalpy-entropy compensation, though never derived from the fundamental thermodynamic relationships, is found so abundantly in various reactions and equilibria and that the reaction rate and equilibrium are independent of any perturbing factors at the specific temperature. However, it seems natural at the same time that chemical events are not controlled exclusively by a single factor but are rather governed by multiple factors correlating each other. 

Grunwald E, Steel C (1995) Solvent reorganization and thermodynamic enthalpy-entropy compensation. J Am Chem Soc 117(21) 5687—5692... 

From strictly formalistic considerations, much larger surface tension changes are achieved in RP-HPLC than in HP-HIC separations of polypeptides and proteins, and these differences underpin the relative facility of these techniques to follow the same types of molecular binding events (and their perturbations) to the same level of physicochemical discrimination. Obviously, analogous approaches linking the interaction thermodynamics and the extrathermodynamic physicochemical properties or enthalpy-entropy compensation phenomena can be developed for the other major HPLC modes,... 

For a full account of the origin and analyses of the kinetic and thermodynamic enthalpy-entropy compensation effect, see Y Inoue, T Wada. In GW Gokel, ed. Advances in Supramolecular Chemistry. Greenwich, CT JAI Press, 1997, 55-96. 

The focus of this review article will be on the interaction between macromolecules and small-molecule ligands. The discussion will first center on the thermodynamic and kinetic characteristics that are used to measure the extent of binding. Subsequently, we discuss the interactions at the atomic level that drive complex formation. Then, a discussion follows of some tools available to predict macroscopic properties from microscopic properties. We then briefly discuss macromolec-ular motions as well as various aspects of receptor-ligand that have attracted renewed attention, such as conformational selection versus induced-fit, enthalpy-entropy compensation effect, and protein allostery. 

Ford DM. Enthalpy-entropy compensation is not a general feature of weak association. J. Am. Chem. Soc. 2005 127 16167-16170. Cooper A. Thermodynamic analysis of biomolecular interactions. Curr. Opin. Chem. Biol. 1999 3 557-563. 

Enthalpy-entropy compensation The free energy of equilibria can be decomposed into an enthalpic and entropic component. In biochemical equilibria, there often is a linear relationship between the enthalpy and the entropy, most intuitively explained by the loss of conformational entropy as binding enthalpy increases the stronger the binding the more rigid the complex. There is still controversy on this topic, however, because it is difficult to measure enthalpy and entropy independently and it is even more difficult to explain thermodynamic phenomena with atomistic models. 

The enthalpy-entropy compensation effect has long been a hot topic in chemical literature, because in principle no explicit relationship between the enthalpy change and the entropy change can be derived from fundamental thermodynamics. Nevertheless, the compensatory enthalpy-entropy relationship has often been observed in both activation and thermodynamic quantities determined for a very wide variety of reactions and equilibria. 

Rekharsky MV, Inoue Y, Chiral recognition thermodynamics of f-cyclodextrin The thermodynamic origin of enantioselectivity and the enthalpy-entropy compensation effect, J. Am. Chem. Soc. 2000 122 4418-4435. 

Inoue Y, Hakushi T, Liu Y, Tong LH, Shen BJ, Jin DS, Thermodynamics of molecular recognition by cyclodextrins. 1. Calorimetric titration of inclusion complexation of naphthalenesulfonates with a-, f-, and y-cyclodextrins enthalpy-entropy compensation, J. Am. Chem. Soc. 1993 115 475-481. 

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