Formal Separation of the Solvent Effects

Formal Separation of the Solvent Effects We consider the association process 

In general, each of the species P, L, and PL can assume many conformations. In this section we treat only one conformation of each species. We shall return to the averaging process over all possible conformations in section 8.7.5. For the moment, Qa does not include the contributions due to internal rotations (or conformations). For the complex PL we also write 

The same reaction (8.7.1), with the same assumed conformations, in an ideal-gas phase would have an equilibrium constant 

Clearly, in the absence of the solvent all of the coupling-work terms are zeros and 5G = 0. 

In this section we shall mainly focus on the 3G oi the association reaction. We shall also compare it with AC/ to get some estimates of the order of magnitude of the different contributions to AG° It is convenient to define a new binding Gibbs energy by 

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