Year: 2006
Type: article
Abstract: Measurements of liquid-liquid phase transition temperatures (cloud points) of mixtures of a protein (lysozyme) and a polymer, poly(ethylene glycol) (PEG) show that the addition of low molecular weight PEG stabilizes the mixture whereas high molecular weight PEG was destabilizing. We demonstrate that this behavior is inconsistent with an entropic lysozyme-PEG depletion interaction and suggest that an energetic lysozyme-PEG attraction is responsible. In order to independently characterize the lysozyme-PEG interactions, light scattering experiments on the same mixtures were performed to measure second and third virial coefficients. These measurements indicate that PEG induces repulsion between lysozyme molecules, contrary to the depletion prediction. Furthermore, it is shown that third virial terms must be included in the mixture's free energy in order to qualitatively capture our data.
Source: Physical Review Letters
Authors: J. Bloustine, T. Virmani, G. M. Thurston, S. Fraden
Institutions: Brandeis University, Rochester Institute of Technology
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Funder: National Eye Institute
OpenAlex ID: W71689619