Integral equation theory for charged liquids: The structure of macroions in solution and the inversion of experimental data

Cold cataracts: a naturally occurring aqueous two-phase system

The cytoplasm of the eye lenses shows a liquid-liquid phase transition similar to the one observed in aqueous two-phase systems. This phenomenon is known as cold cataracts. We have studied the solution behavior of the main protein fractions that constitute the lenses' cytoplasm using small-angle neutron scattering and dynamic light scattering. Our results provide evidence that an intricate balance of forces underlines the physical phenomena responsible for the optical properties of the lenses and for the phase transition that is observed as the temperature is lowered below some critical value. These forces include solvent-mediated forces besides the more conventional Coulombic and dispersion forces. This study suggests that solvent mediated forces must be included to successfully model liquid-liquid phase transitions like the ones observed in cold cataracts or in aqueous two-phase systems.

A small-angle neutron scattering study of gamma-crystallins near their isoelectric point

In this paper, a small-angle neutron scattering study of gammaII-crystallins near their isoelectric point is presented. The experiments were carried out using protein concentrations of 5.7-85.7 mg/ml at temperatures in the range 11 -60 degrees C. The experimental data were analyzed using an ellipsoidal model for intraparticle correlations and the mean spherical approximation for interparticle correlations. Our studies revealed that gammaII-crystallins have a thick hydration layer, which is possibly due to the special arrangement of polar and ionic groups on their surface. The temperature scan shows that, as a result of relatively strong attractive forces, clusters of two, three, or higher oligomers are present below 20 degrees C. Our results suggest that protein clusters, with a distinctive hydration layer, form a protein-rich phase that separates from a protein-lean phase as the temperature is decreased below some threshold value.