AMI seminar: Anna Stradner

Room 170.048, Adolphe Merkle Institute, Marly

Thursday, January 28th, 2010  16:00 h

Cataract formation from a colloid physicist's viewpoint

PD Dr. Anna Stradner

Adolphe Merkle Institute, Fribourg University, Marly

Understanding interparticle interactions in protein solutions is of central importance to gain insight into the origin of protein condensation diseases such as Creutzfeldt Jakob, Alzheimer, Parkinson or cataract, the leading cause of blindness worldwide. The eye lens proteins gamma-crystallin and alpha-crystallin are particularly interesting and important, as they are ideally suited for an attempt to use well-defined proteins with easily tuneable interaction potentials as model systems for colloids as well as because of their biological and medical relevance for cataract formation. Here we present results from a study of the structural and dynamic properties of these lens protein solutions up to concentrations corresponding to those found in the eye lens using small-angle neutron (SANS) and X-ray scattering (SAXS) combined with light scattering, rheological measurements and molecular dynamics simulations. We discuss the results in the context of simple models from colloid science and demonstrate that they indeed allow us to interpret the complex protein phase diagrams. We show that transparency of lens crystallin protein mixtures at high concentrations, comparable to those in the living eye lens, is greatly enhanced by weak, short-range attractions between two of the prevalent mammalian crystallins, alpha- and gamma-crystallin. Provided they are not too strong, such mutual attractions considerably decrease the critical temperature and corresponding opacity due to light scattering, and are thus essential for lens transparency.