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Enthalpy-entropy compensation: a phantom or something useful?

Evgeni B Starikov¹, Bengt Nordén

¹Institute for Nanotechnology, Research Center Karlsruhe, Post Box 3640, D-76021 Karlsruhe, Germany. starikow@chemie.fu-berlin.de

The Journal of Physical Chemistry. B

|November 30, 2007

Summary

Enthalpy-entropy compensation (EEC) may be explained by micro-phase transitions (MPTs) within a Carnot-cycle model. This offers a physical basis for EEC in cooperative processes like protein folding and molecular motor function.

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Area of Science:

Chemical Thermodynamics
Physical Chemistry
Biophysics

Background:

Enthalpy-entropy compensation (EEC) is a common observation in chemical systems, but its physical origins remain debated.
The phenomenon is often questioned as a potential artifact of mathematical correlations or data misinterpretation rather than a true physical effect.

Purpose of the Study:

To re-evaluate enthalpy-entropy compensation (EEC) from a novel perspective.
To propose a physically grounded explanation for EEC, moving beyond mathematical coincidences.

Main Methods:

Review of existing literature on EEC.
Development of a theoretical framework based on a Carnot-cycle model.
Identification of micro-phase transitions (MPTs) as key factors.

Main Results:

EEC can be rationalized through hidden, physically real factors within a Carnot-cycle model.
Micro-phase transitions (MPTs) are identified as crucial elements underlying physically valid EEC.
Examples include changes in structured water at hydrophobic surfaces and conformational changes in ligand-biopolymer binding.

Conclusions:

The micro-phase transition (MPT) concept provides a robust explanation for EEC.
This framework can rationalize EEC in biological phenomena such as protein hydration, folding, and molecular motor operation.