The thermodynamic analyses of proteins, protein-ligands and protein-nucleic acid complexes
involves the entropy–enthalpy (S-H) compensation phenomenon. We have examined the question
whether the observed compensation is artificial or reflects anything more than the well-known laws of
statistical thermodynamics (so-called extra-thermodynamic compensation). We have shown that enthalpy−
entropy compensation (EEC) is mainly the trivial consequence of the basic thermodynamic laws
and there are no experimental evidences for existence of the extra-thermodynamic compensation. In
most cases EEC obtained in the experiments through the plot enthalpies (ΔH) and entropies (TΔS) versus
one another is meaningless due to the large correlated errors in ΔH and TΔS, unless special
measures are taken to minimize, quantify and propagate these errors. Van’t Hoff equation can be used
for entropy calculation in limited cases when enthalpy is measured in independent experiments. Eyring
equation cannot be used for calculation of entropy in any case and should be excluded from scientific
use. Both equation, Van’t Hoff and Eyring cannot be used for simultaneous calculation of the enthalpy
and entropy values using one set of data. All the data obtained in this way should be recognized as erroneous.
Keywords: Entropy-enthalpy compensation, protein thermodynamics, thermodynamic equations, evidences.
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