タンパク質―リガンド相互作用の熱測定

概要

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The most common term which is used for interpreting the physicochemical processes is obviously the free energy change. However, for detailed interpretation they should be discussed in terms of both the enthalpy and entropy values rather than the free energy data alone.<BR>It is obvious that the enthalpy values can be most accurately determined by direct calorimetry. Recent development in the calorimetric techniques have enabled their application to the various biochemical processes. In this article calorimetric studies of protein-ligand interaction are reviewed.<BR>When the calorimetric measurements are performed at different ligand concentrations, a thermal titration curve is obtained. This method is employed for the analysis of binding site involved in various enzyme and protein molecules.<BR>Temperature dependence of enthalpy changes gives a heat capacity change. A large negative value is often observed in the protein-ligand interaction. A magnitude of the heat capacity data is attributed to a change in protein structure accompanied by the ligand-binding.<BR>When an ionizable group of a protein molecule participates in the binding reaction, the enthalpy change varies with pH. Thus the enthalpy values obtained at different pHs gives an information about the role of ionizable amino acid residue in the binding site.
日本生物物理学会の論文