Random solvation

Desolvation of the reacting polar groups is also a mechanism by which enzymes achieve rate accelerations. The desolvation of functional groups takes places during the inclusion of the reactants within the catalytic apparatus of the active site. This is another way of looking at the selective stabilization of the TS, in terms of a specific solvation of the reactants by the enzyme residues of the active site, which replaces the random solvation by the solvent molecules and the inherent enthalpic and entropic cost associated with their reorganization in the TS. 

The randomly occupied lattice model of a polymer solution used in the Rory-Huggins theory is not a good model of a real polymer solution, particularly at low concentration. In reality, such a solution must consist of regions of pure solvent interspersed with locally concentrated domains of solvated polymer. 

Dissolution of a MA/TBSM mixture in DMFA leads to dissociation of the complexes and hence shifts the reaction towards the formation of random copolymers or the propagation reaction is inhibited by the competing solvatation effect of the solvent. 

Fig. 6. Spectral monitoring of the thermal denaturation of the highly helical, Ala-rich peptide Ac-(AAAAK)3AAAA-YNH2 in D20 from 5 to 60°C, as followed by changes in the amide V IR (left) and VCD (right). IR show a clear shift to higher wavenumber from the dominant a-helical peak (here at an unusually low value, 1637 cm-1, due to full solvation of the helix) to a typical random coil value ( 1645 cm-1). VCD loses the (—,+,—) low-temperature helical pattern to yield a broad negative couplet, characteristic of a disordered coil, at high temperature. Spectra were normalized to A = 1.0 by 45°C.

In general, pores swell nonuniformly. As a simplification, fhe random network was assumed to consist of fwo types of pores. In fhis fwo-stafe model, nonswollen or "dry" pores (referred to later as "red" pores) permit only a small residual conductance due to tightly bound surface water, which solvates the charged surface groups. Swollen or "wet" pores (referred to later as "blue" pores) contain extra water in the bulk, allowing them to promote the high bulk-like conductance. Water uptake by the membrane corresponds to the swelling of wef pores and to the increase of their relative fraction. 

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