Isothermal observed binding enthalpy

The enthalpy and entropy of binding can be determined experimentally, as, for example, by isothermal titration calorimetry (46,471. These data, however, are still sparse and not always easy to interpret (48, 49). Substantial compensation between enthalpic and entropic contributions is observed (50-52) this phenomenon and its interpretations have recently been critically reexamined (53). Interestingly, the data also show that binding can be both enthalpy-driven (e.g., streptavidin-biotin, AG = -76.5 kJ/mol, AH = -134 kJ/mol) or entropy-driven (e.g., streptavidin-HABA, AG = -22.0 kJ/mol, AH = +7.1 kJ/mol) (54). However, because cf strong temperature dependencies, even this partitioning is a question of the temperature used for measuring. 

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