Free binding enthalpy

Armentrout and Rogers also suggest more suitable anchor points for the LCA scale, e.g. the lithium cation bond energies to methanol or dimethyl ether. They further examined the kinetic energy dependences of the CID of Li+—ROH with and reported that the dominant dissociation process in all cases is the loss of alcohol. The thresholds for Li+—ROH dissociations were determined and converted to enthalpies and free energies at 298 and 373 K for comparison with previous equihbrium data on these systems. LCA values at 298 K for a series of alcohols are summarized in Table 3. The experimental results are compared with enthalpies of binding (PA) at 298 K (Figure 2) and a linear correlation between the LCA and the PA is found. 

Isothermal titration calorimetry (ITC) measures heats of association for ligand complexation as one component is titrated into the other. ITC measurements provide direct determination of the number of binding sites, n, the enthalpy of binding, AH, and the association constant, K. The association constant can then be used to determine the free energy, AG, from which entropic contributions, AS, to binding can be calculated. This technique offers the benefit that titration can be done in solution and has been used extensively to characterize the thermodynamic contributions of multivalent ligand binding to proteins. ... 

AGb is Gibbs free enthalpy of binding, A//b enthalpy of binding, T absolute temperature, ASb entropy of binding, and R gas constant. 

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