LIGHT-SCATTERING BY BOVINE ALPHA-CRYSTALLIN PROTEINS IN SOLUTION - HYDRODYNAMIC STRUCTURE AND INTERPARTICLE INTERACTION

We have studied diluted bovine eye lens alpha-crystallin solutions by using light scattering. The protein particles were modeled as hard sph eres, showing electrostatic repulsion, due to surplus electric charges , and weak attractive interaction. The repulsive potential V-R is defi ned by the radius of the particles, the Debye length K-1, and the numb er of charges at the Gouy layer; the attractive potential has been des cribed by the London-van der Waals potential and is defined by the Ham aker constant A. We have used the diluted gas approximation and the on e component macrofluid model to relate the experimental static factor K-1 to the theoretical expression of the interaction potential V(x). T his resulted in a Hamaker constant A of 0.06 +/- 0.01 KBT and an effec tive charge q ranging from 18 +/- 1 at low ionic strength (Omega = 0.0 022 M) to 50 +/- 5 at high ionic strength(Omega = 0.1472M).