• Schurtenberger, Peter
• Foffi, Guiseppe
• Savin, Gabriela
• Stradner, Anna
• Bucciarelli, Saskia
• Dorsaz, Nicolas
• Thurston, George M.

Abstract

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 scat- tering data and small-angle X-ray scattering liquid structure data from α-crystallin solutions over an extended range of protein con- centrations up to 290 mg/mL or 49% vol fraction and up to ca. 330 mg/mL for static light scattering. The measured dynamic light scat- tering 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 frac- tions 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 sim- ulations of polydisperse hard-sphere systems and use mode-cou- pling theory to compare the measured dynamic power laws with those of hard-sphere models. The static and dynamic data, sim- ulations, 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 mo- lecular basis of presbyopia and the kinetics of molecular change during cataractogenesis.

Topics

• impedance spectroscopy
• theory
• simulation
• glass
• glass
• molecular dynamics
• viscosity
• selective ion monitoring
• X-ray scattering
• dynamic light scattering
• static light scattering
• viscometry