DOI: 10.1140/epje/i2002-10047-7
Catching the PEG-induced attractive interaction between proteins
D. Vivarès1, L. Belloni2, A. Tardieu1 and F. Bonneté31 LMCP- UMR7590, case 115, 4 place Jussieu, F-75252 Paris Cedex 05, France
2 CEA-Saclay, Service de Chimie Moléculaire, F-91191 Gif-sur-Yvette, France
3 CRMC2 (Laboratory associated to Universities Aix-Marseille II and III.) -CNRS, Campus de Luminy, case 913, F-13288 Marseille Cedex 09, France
vivares@crmc2.univ-mrs.fr
bonnete@crmc2.univ-mrs.fr
(Received 29 April 2002 / Published online: 29 October 2002)
Abstract
We present the experimental and theoretical background of
a method to characterize the protein-protein attractive potential induced by
one of the mostly used crystallizing agents in the protein-field, the
poly(ethylene glycol) (PEG). This attractive interaction is commonly called,
in colloid physics, the depletion interaction. Small-Angle X-ray Scattering
experiments and numerical treatments based on liquid-state theories were
performed on urate oxidase-PEG mixtures with two different PEGs (3350 Da and
8000 Da). A "two-component" approach was used in which the polymer-polymer,
the protein-polymer and the protein-protein pair potentials were determined.
The resulting effective protein-protein potential was characterized. This
potential is the sum of the free-polymer protein-protein potential and of
the PEG-induced depletion potential. The depletion potential was found to be
hardly dependent upon the protein concentration but strongly function of the
polymer size and concentration. Our results were also compared with two
models, which give an analytic expression for the depletion potential.
87.15.Nn - Properties of solutions; aggregation and crystallization of macromolecules.
87.15.Aa - Theory and modeling; computer simulation.
83.85.Hf - X-ray and neutron scattering.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002
