8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P4.62Fri 911:10-14:00Effect of additives on protein phase behaviourDana Wagner 11 Heinrich-Heine Universität Düsseldorf, Universitätsstra 1, Insititut für Physik der weichenMaterie (IPKM) 40225, Düsseldorf, GermanyThe phase behaviour of protein solutions has been studied, employing lysozyme as a model systemand the results have been compared to theoretical predictions based on the Derjaguin-Landau-Verwey-Overbeek (DLVO) effective protein pair potential. In particular the effect of additives suchas glycerol, dimethyl sulfoxide (DMSO) and ethanol has been examined. Glycerol is widely usedas an additive to stabilise proteins in aqueous solution. Both the crystallisation boundary and themetastable liquid-liquid phase separation are found to shift to lower temperatures upon the additionof glycerol. In agreement with previous studies, this is interpreted as evidence that glycerol inducesa repulsive interaction between protein molecules. This effect is quantified in terms of the secondvirial coefficient, B 2, which was determined from static light scattering experiments. If B 2 isused as a control parameter instead of temperature, the phase boundaries of protein solutions withdifferent additives show a general dependence on protein concentration.62