Separable equilibrium solvation model

Extensive literature has developed related to the preferential interaction of different solvents with proteins or peptides in bulk solution.156-5X1 Similar concepts can be incorporated into descriptions of the RPC behavior of peptides and employed as part of the selection criteria for optimizing the separation of a particular peptide mixture. As noted previously, the dependency of the equilibrium association constant, /CassoCji, of a peptide and the concentration of the solvent required for desorption in RPC can be empirically described1441 in terms of nonmechanistic, stoichiometric solvent displacement or preferential hydration models, whereby the mass distribution of a peptide P, with n nonpolar ligands, each of which is solvated with solvent molecules Da is given by the following ... 

In the early 50 s, an ion pair model was introduced by Winstein to rationalize the mechanism and stereochemistry of solvolysis of sulfonates72). This research of carbocationic intermediates and the role of ion solvation equilibrium in reaction mechanisms represents a landmark in the study of charged species. These thermodynamically different ionic species were coined as free ions, contact ion-pairs (c.i.p.), and solvent-separated ion pairs (s.s.i.p.). The ion pair situation can be described as an equilibrium between thermodynamically distinct contact (c.i.p.) and solvent-separated ion pairs (s.s.i.p.) 2-l3 16 The situation should be represented by a continuum of ion-solvation equilibria states in which the two extreme states are the c.i.p. and the s.s.i.p. 2 76) (Eq. 12)... 

As part of their molecular-based investigation of solvation at supercritical conditions, Chialvo et al. [230] performed molecular dynamics simulations of supercritical electrolyte solutions with three different ion-water models toward the determination of the association constant for the ion pair Na lCF and the equilibrium constant of association between the solvent-separated and the contact... 

In macromolecular system (e.g. in polypeptides, proteins, etc.) a dominant part of the solvent effect is due to the solvent dependence of the conformation of the molecule. To separate this effect from that of the differences in solvation of functional groups, alteration of the relative permittivity of the system, etc., equilibrium constants of analogous processes measured in macrorao-lecular systems and in analogous model systems of low molecular... 

The current SDEL algorithm uses an implicit solvent model. This is not a fatal flaw of SDEL computations of trajectories with an atomistic description of the environment are possible. The assumption of time separation between the relaxation to equilibrium of water molecules and the solvated molecule (e.g., a protein) makes the calculations viable. The configuration for the water molecules can then be determined using a... 

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