Unusual dynamics of concentration fluctuations in solutions of weakly attractive globular proteins.
The globular protein γB-crystallin exhibits a complex phase behavior, where liquid-liquid phase separation characterized by a critical volume fraction ϕc = 0.154 and a critical temperature Tc = 291.8 K coexists with dynamical arrest on all length scales at volume fractions around ϕ ≈ 0.3-0.35, and an arrest line that extends well into the unstable region below the spinodal. However, although the static properties such as the osmotic compressibility and the static correlation length are in quantitative agreement with predictions for binary liquid mixtures, this is not the case for the dynamics of concentration fluctuations described by the dynamic structure factor S(q,t). Using a combination of dynamic light scattering and neutron spin echo measurements, we demonstrate that the competition between critical slowing down and dynamical arrest results in a much more complex wave vector dependence of S(q,t) than previously anticipated.
Physical Chemistry, Department of Chemistry, Lund University , SE-22100 Lund, Sweden.
Saskia
S
Bucciarelli
Physical Chemistry, Department of Chemistry, Lund University , SE-22100 Lund, Sweden.
Lucía
L
Casal-Dujat
Department of Physics, Università di Roma La Sapienza , I-00186 Roma, Italy.
Cristiano
C
De Michele
Department of Physics, Università di Roma La Sapienza , I-00186 Roma, Italy.|CNR-ISC Uos, Università di Roma La Sapienza , I-00186 Roma, Italy.
Francesco
F
Sciortino
Forschungszentrum Jülich, Institute of Complex Systems (ICS), Soft Condensed Matter (ICS-3), D-52425 Jülich, Germany.|Heinrich-Heine-Universität Düsseldorf , Department of Physics, D-40225 Düsseldorf, Germany.
Jan
J
Dhont
Physical Chemistry, Department of Chemistry, Lund University , SE-22100 Lund, Sweden.|Department of Chemistry and Molecular Biology, University of Gothenburg , SE-41296 Göteborg, Sweden.
Johan
J
Bergenholtz
Institut Laue-Langevin , F-38042 Grenoble Cedex 9, France.
Bela
B
Farago
Physical Chemistry, Department of Chemistry, Lund University , SE-22100 Lund, Sweden.
Peter
P
Schurtenberger
Physical Chemistry, Department of Chemistry, Lund University , SE-22100 Lund, Sweden.
Anna
A
Stradner
D000818:Animals; D002417:Cattle; D017510:Protein Folding; D011506:Proteins / Q000737:chemistry*; D012996:Solutions; D038222:gamma-Crystallins / Q000737:chemistry*
D011506:Proteins; D012996:Solutions; C107738:crystallin, gammaB; D038222:gamma-Crystallins
arrest transition; critical phenomena; dynamic light scattering; lens proteins; neutron spin echo; protein dynamics