Volume 77, Number 4, February 2007
Article Number 48004
Number of page(s) 5
Section Interdisciplinary Physics and Related Areas of Science and Technology
Published online 09 February 2007
EPL, 77 (2007) 48004
DOI: 10.1209/0295-5075/77/48004

Modeling equilibrium clusters in lysozyme solutions

F. Cardinaux1, A. Stradner1, P. Schurtenberger1, F. Sciortino2 and E. Zaccarelli2

1  Department of Physics, University of Fribourg - CH-1700 Fribourg, Switzerland
2  Dipartimento di Fisica and CNR-INFM-SOFT, Università di Roma La Sapienza - Rome, Italy

received 15 November 2006; accepted in final form 19 December 2006; published February 2007
published online 9 February 2007

We present a combined experimental and numerical study of the equilibrium cluster formation in globular-protein solutions under no-added salt conditions. We show that a cluster phase emerges as a result of a competition between a long-range screened Coulomb repulsion and a short-range attraction. A simple effective potential, in which electrostatic repulsion is fixed by experimental conditions and attraction is modeled with a generalized Lennard-Jones potential, accounts in a remarkable way for the wavevector dependence of the X-ray scattering structure factor.

87.14.Ee - Proteins.
61.10.Eq - X-ray scattering (including small-angle scattering).
61.20.Ja - Computer simulation of liquid structure.

© Europhysics Letters Association 2007