Poly(ethylene glycol)-induced shrinkage of Sephadex gel. A model system for quantitative analysis of osmoelastic coupling.

Shrinkage of Sephadex gels caused by addition of a high-molecular weight molecule, poly(ethylene glycol) (PEG) was studied. A quantitative analysis based on the cross-linked network theory by Flory and Tanaka (Tanaka, T. 1978. Phys. Rev. Lett. 40:820-823) showed that the shrinkage is due to a mechanochemical coupling between the elasticity of the network and the osmotic stress arising from preferential exclusion of PEG. These results may provide good evidence for "osmoelastic coupling", the coupling between elasticity of macromolecular structures and osmotic stress, which has been predicted in some biological systems such as phospholipid bilayer membranes (Ito, T., M. Yamazaki, and S. Ohnishi. 1989. Biochemistry. 28:5626-5630; Yamazaki, M., S. Ohnishi, and T. Ito. 1989. Biochemistry. 28:3710-3715) or actin filaments.