Researchers come closer to pinpointing what causes cataract

November 14th, 2007 - 10:23 am ICT by admin  

The eye lens is made up of densely packed crystallin proteins, arranged in such a way that light in the visible wavelength range can pass through.

However, for various reasons, including UV radiation exposure and age, the proteins sometimes change their behaviour and clump together. Such changes cause the light entering the lens to scatter, resulting in cloudy vision or blindness.

As of now, scientists do not know how to reverse the protein aggregation process once it has begun.

In a previous study, it had been found that the interactions between the three major crystallin proteins, which make up the concentrated eye lens protein solution, were key to cataract formation.

In the latest study, the scientists used a combination of neutron scattering experiments and molecular dynamics computer simulations to study the interactions between two of the major crystallin proteins, at concentrations similar to those found in the eye lens.

They found that a finely tuned combination of attraction and repulsion between the two proteins resulted in an arrangement that was transparent to visible light.

“By combining experiments and simulations it became possible to quantify that there had to be a weak attraction between the proteins in order for the eye lens to be transparent. Our results indicate that cataracts may form if this balance of attractions is disrupted, and this opens a new direction for research into cataract formation,” said EPFL postdoctoral researcher Giuseppe Foffi, a member of the Institut Romand de Recherche Numerique en Physique des Materiaux (IRRMA).

University of Fribourg physicist and lead author Anna Stradner said: “Lots of studies have been done on individual proteins in the lens. But none on their mixtures at concentrations typically found in the eye. We modelled these proteins as colloidal particles, and found there was a very narrow window in which the protein solution remained stable, and this was a necessary condition for lens transparency.”

The researchers say that besides providing important new information about the interactions of the proteins in the eye lens, the their study provides a framework for further research into the molecular properties and interactions of proteins.

They also believe that the properties of the proteins’ mixture may perhaps be manipulated to prevent or reverse aggregation. (ANI)

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