Hard sphere-like glass transition in eye lens α-crystallin solutions.
We study the equilibrium liquid structure and dynamics of dilute and concentrated bovine eye lens α-crystallin solutions, using small-angle X-ray scattering, static and dynamic light scattering, viscometry, molecular dynamics simulations, and mode-coupling theory. We find that a polydisperse Percus-Yevick hard-sphere liquid-structure model accurately reproduces both static light scattering data and small-angle X-ray scattering liquid structure data from α-crystallin solutions over an extended range of protein concentrations up to 290 mg/mL or 49% vol fraction and up to ca. 330 mg/mL for static light scattering. The measured dynamic light scattering and viscosity properties are also consistent with those of hard-sphere colloids and show power laws characteristic of an approach toward a glass transition at α-crystallin volume fractions near 58%. Dynamic light scattering at a volume fraction beyond the glass transition indicates formation of an arrested state. We further perform event-driven molecular dynamics simulations of polydisperse hard-sphere systems and use mode-coupling theory to compare the measured dynamic power laws with those of hard-sphere models. The static and dynamic data, simulations, and analysis show that aqueous eye lens α-crystallin solutions exhibit a glass transition at high concentrations that is similar to those found in hard-sphere colloidal systems. The α-crystallin glass transition could have implications for the molecular basis of presbyopia and the kinetics of molecular change during cataractogenesis.
Laboratoire de Physique de Solides, UMR 8502, Université Paris-Sud, F-91405 Orsay, France;
Giuseppe
http://orcid.org/0000-0002-7444-1453
G
Foffi
Physics Department and Fribourg Center for Nanomaterials, University of Fribourg, CH-1700 Fribourg, Switzerland;
Gabriela
G
Savin
Physical Chemistry, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden;
Saskia
S
Bucciarelli
Institute of Theoretical Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland; and.
Nicolas
N
Dorsaz
School of Physics and Astronomy, Rochester Institute of Technology, Rochester, NY 14623-5603 georgemthurston@gmail.com anna.stradner@fkem1.lu.se.
George M
GM
Thurston
Physical Chemistry, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden; georgemthurston@gmail.com anna.stradner@fkem1.lu.se.
Anna
A
Stradner
Physical Chemistry, Department of Chemistry, Lund University, SE-221 00 Lund, Sweden;
Peter
P
Schurtenberger
D000818:Animals; D002417:Cattle; D007908:Lens, Crystalline / Q000378:metabolism*; D012542:Scattering, Radiation; D014783:Viscosity; D038201:alpha-Crystallins / Q000737:chemistry / Q000378:metabolism*
D038201:alpha-Crystallins
alpha crystallin; glass transition; mode-coupling theory; molecular dynamics; scattering