Macromolecule hydration and the effect of solutes on the cloud point of aqueous solutions of polyvinyl methyl ether: A possible model for protein denaturation and temperature control in homeothermic animals

Abstract

The effects of strong, neutral, 1:1 electrolytes; MgSO 4; urea, tetraalkylammonium salts, sucrose, and alcohols on the cloud point temperature of aqueous solutions of polyvinyl methyl ether have been examined and are interpreted in terms of (1) the two types of water structure, coulombic and hydrophobic, comprising the hydration sheath of polymer, (2) the selective exclusion of solute from the polymer's hydration sheath, and (3) the solute's stabilization or destabilization of the polymer's hydration sheath. The last two of these processes are related to the viscosity B-coefficient of the solute ions. The behavior of the polymer exhibits both similarities to and differences from proteins, and caution must be exercised in the use of the cloud point phenomenon as a model of protein denaturation. The solute effects described in this paper suggest a possible experimental test of the hypothesis that the thermal destruction of a biopolymer's hydration sheath might provide the basis of temperature control in homeothermic animals.