Kinetics of liquid-liquid phase separation in protein solutions exhibiting LCST phase behavior studied by time-resolved USAXS and VSANS.
We study the kinetics of the liquid-liquid phase separation (LLPS) and its arrest in protein solutions exhibiting a lower critical solution temperature (LCST) phase behavior using the combination of ultra-small angle X-ray scattering (USAXS) and very-small angle neutron scattering (VSANS). We employ a previously established model system consisting of bovine serum albumin (BSA) solutions with YCl3. We follow the phase transition from sub-second to 104s upon an off-critical temperature jump. After a temperature jump, the USAXS profiles exhibit a peak that grows in intensity and shifts to lower q values with time. Below 45 °C, the characteristic length scale (ξ) obtained from this scattering peak increases with time with a power of about 1/3 for different sample compositions. This is in good agreement with the theoretical prediction for the intermediate stage of spinodal decomposition where the growth is driven by interface tension. Above 45 °C, ξ follows initially the 1/3 power law growth, then undergoes a significant slowdown, and an arrested state is reached below the denaturation temperature of the protein. This growth kinetics may indicate that the final composition of the protein-rich phase is located close to the high density branch of the LLPS binodal when a kinetically arrested state is reached.
Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany. fajun.zhang@uni-tuebingen.de.
Stefano
http://orcid.org/0000-0002-1700-4759
S
Da Vela
Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany. fajun.zhang@uni-tuebingen.de.
Michal K
MK
Braun
Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany. fajun.zhang@uni-tuebingen.de.
Andreas
A
Dörr
Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany. fajun.zhang@uni-tuebingen.de.
Alessandro
A
Greco
European Synchrotron Radiation Facility, 71 avenue des Martyrs, 38043 Grenoble Cedex 9, France.
Johannes
http://orcid.org/0000-0001-8363-9077
J
Möller
Forschungszentrum Jülich GmbH, JCNS@MLZ, Lichtenbergstrasse 1, 85747, Garching, Germany.
Zhendong
Z
Fu
Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany. fajun.zhang@uni-tuebingen.de.
Fajun
F
Zhang
Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany. fajun.zhang@uni-tuebingen.de.
Frank
F
Schreiber
D007700:Kinetics; D044367:Phase Transition; D011506:Proteins / Q000737:chemistry*; D053838:Scattering, Small Angle; D012996:Solutions; D013696:Temperature
D011506:Proteins; D012996:Solutions