Regensburg 2016 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 4: Colloids and Complex Fluids I (Joint Session BP/CPP/DY)
BP 4.2: Vortrag
Montag, 7. März 2016, 09:45–10:00, H45
Phase behavior of dense lysozyme solutions — •Julian Schulze1, Johannes Möller2, Michael Paulus1, Julia Nase1, Metin Tolan1, and Roland Winter3 — 1Fakultät Physik/Delta, Technische Universität Dortmund,44221 Dortmund ,Germany — 2ESRF - The European Synchrotron, 38043 Grenoble, France — 3Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, 44221 Dortmund, Germany
In previous studies, small-angle X-ray scattering (SAXS) in combination with liquid-state theoretical approaches and DLVO theory was used to study the intermolecular interaction potential V(r) of lysozyme solutions under the influence of varying environmental conditions such as protein concentration c, temperature T, and pressure p. While the repulsive Coulomb term of the DLVO potential remains almost constant as a function of p, the depth of the attractive part, J(p), exhibits a non-monotonic p-dependence with a minimum at about 2 kbar at constant T. Adding 0.5 M NaCl leads to more prominent short range interactions, especially at high c and low T, and the homogeneous protein solution becomes turbid due to formation of a metastable liquid-liquid phase separation (LLPS) region, where lysozyme forms small droplets of high concentration within the more dilute liquid phase. At elevated pressures, this l-l phase separation is suppressed, but due to the non-monotonic behavior of J(p), a further pressure increase leads to a re-entrant LLPS regime. In this contribution, we will discuss the phase behavior of lysozyme as a function of c, p, and T.