title: Osmotic pressures of lysozyme solutions from gas-like to crystal states.
abstract: We obtained osmotic pressure data of lysozyme solutions, describing their physical states over a wide concentration range, using osmotic stress for pressures between 0.05 bar and about 40 bar and volume fractions between 0.01 and 0.61. The osmotic pressure vs. volume fraction data consist of a dilute, gas-phase regime, a transition regime with a high-compressibility plateau, and a concentrated regime where the system is nearly incompressible. The first two regimes are shifted towards a higher protein volume fraction upon decreasing the strength or the range of electrostatic interactions. We describe this shift and the overall shape of the experimental data in these two regimes through a model accounting for a steric repulsion, a short-range van der Waals attraction and a screened electrostatic repulsion. The transition is caused by crystallization, as shown by small-angle X-ray scattering. We verified that our data points correspond to thermodynamic equilibria, and thus that they consist of the reference experimental counterpart of a thermodynamic equation of state.
authors.affiliation: STLO, Agrocampus Ouest, INRA, 35000, Rennes, France. stephane.pezennec@inra.fr and Institut de Physique de Rennes, UMR6251 CNRS-Université de Rennes 1, F-35042 Rennes, France.
authors.forename: Coralie
authors.initials: C
authors.lastname: Pasquier
authors.affiliation: Institut de Physique de Rennes, UMR6251 CNRS-Université de Rennes 1, F-35042 Rennes, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Beaufils
authors.affiliation: STLO, Agrocampus Ouest, INRA, 35000, Rennes, France. stephane.pezennec@inra.fr and LISBP, UMR 5504/792 INRA-CNRS-INSA, 135 avenue de Rangueil, F-31077 Toulouse CEDEX 04, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Bouchoux
authors.affiliation: STLO, Agrocampus Ouest, INRA, 35000, Rennes, France. stephane.pezennec@inra.fr.
authors.forename: Sophie
authors.initials: S
authors.lastname: Rigault
authors.affiliation: Laboratoire CBI, CNRS UMR 8231, Université Pierre et Marie Curie, Université Diderot, ESPCI, 10 rue Vauquelin, F-75231, Paris CEDEX 05, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Cabane
authors.affiliation: Department of Theoretical Chemistry, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.
authors.forename: Mikael
authors.initials: M
authors.lastname: Lund
authors.affiliation: STLO, Agrocampus Ouest, INRA, 35000, Rennes, France. stephane.pezennec@inra.fr.
authors.forename: Valérie
authors.initials: V
authors.lastname: Lechevalier
authors.affiliation: STLO, Agrocampus Ouest, INRA, 35000, Rennes, France. stephane.pezennec@inra.fr.
authors.forename: Cécile
authors.initials: C
authors.lastname: Le Floch-Fouéré
authors.affiliation: STLO, Agrocampus Ouest, INRA, 35000, Rennes, France. stephane.pezennec@inra.fr.
authors.forename: Maryvonne
authors.initials: M
authors.lastname: Pasco
authors.affiliation: Institut de Physique de Rennes, UMR6251 CNRS-Université de Rennes 1, F-35042 Rennes, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Pabœuf
authors.affiliation: Synchrotron SOLEIL, F-91192 Gif-sur-Yvette, France.
authors.forename: Javier
authors.initials: J
authors.lastname: Pérez
authors.affiliation: STLO, Agrocampus Ouest, INRA, 35000, Rennes, France. stephane.pezennec@inra.fr.
authors.forename: Stéphane
authors.identifier: http://orcid.org/0000-0003-1265-8048
authors.initials: S
authors.lastname: Pezennec