Abstract
Purpose: :
Previous studies have suggested possible weak noncovalent interactions between human alpha crystallins and beta crystallins are necessary for lens transparency. These interactions may be altered after age–dependent or cataract–dependent deamidation. Microequilibrium dialysis was used to ascertain the existence of such interactions under true equilibrium conditions, in contrast to widely used gel filtration chromatographic studies.
Methods: :
One chamber of a microdialysis cell was loaded with human alpha crystallins and recombinant wild–type or deamidation human betaB2 crystallins (Q70E, Q162E). This chamber was separated from the second chamber by a 100KDa molecular weight cut–off membrane. After 5 days at 37oC, samples from each side were collected and the amount of ßB2 crystallin quantitated by reverse phase chromatography.
Results: :
There was no statistical difference in the amounts of betaB2 crystallins in the two microequilibrium dialysis chambers, before or after deamidation.
Conclusions: :
Although previous studies have suggested possible noncovalent interactions between alpha and betaB2 crystallins, microequilibrium dialysis studies under true equilibrium conditions demonstrate no interactions of alpha crystallins with wild–type, Q70E, or Q162E forms of betaB2 crystallins, suggesting that interactions between alpha crystallins and these proteins may not play an important role in the transparent properties of the lens.
Keywords: crystalline lens • protein structure/function • protein modifications-post translational