Cluster-Driven Dynamical Arrest in Concentrated Lysozyme Solutions

We present a detailed experimental and numerical study of the structural and dynamical properties of salt-free lysozyme solutions. In particular, by combining small-angle X-ray scattering (SAXS) data with neutron spin echo (NSE) and rheology experiments, we are able to identify that an arrest transition takes place at intermediate densities, driven by the slowing down of the cluster motion. Using an effective pair potential among proteins, based on the combination of short-range attraction and long-range repulsion, we account remarkably well for the peculiar volume fraction dependence of the effective structure factor measured by SAXS. We show that a transition from a monomer to a cluster-dominated fluid happens at volume fractions larger than phi greater than or similar to 0.05 where the close agreement between NSE measurements and Brownian dynamics simulations confirms the transient nature of the clusters. Clusters even stay transient above the geometric percolation found in simulation at phi > 0.15, though NSE reveals a cluster lifetime that becomes increasingly large and indicates a divergence of the diffusivity at phi greater than or similar to 0.26. Macroscopic measurements of the viscosity confirm this transition where the long-lived-nature of the clusters is at the origin of the simultaneous dynamical arrest at all length scales.

Zaccarelli, Emanuela (author)
Stradner, Anna (author)
Bucciarelli, Saskia (author)
Farago, Bela (author)
Egelhaaf, Stefan U. (author)
Sciortino, Francesco (author)
Schurtenberger, PeterLund University,Lunds universitet,Fysikalisk kemi,Enheten för fysikalisk och teoretisk kemi,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Physical Chemistry,Physical and theoretical chemistry,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH(Swepub:lu)fkem-psh (author)
Fysikalisk kemiEnheten för fysikalisk och teoretisk kemi (creator_code:org_t)

In:The Journal of Physical Chemistry Part B: American Chemical Society (ACS)115:22, s. 7227-72371520-52071520-6106

By the author/editor: Cardinaux, Frede ...; Zaccarelli, Eman ...; Stradner, Anna; Bucciarelli, Sas ...; Farago, Bela; Egelhaaf, Stefan ...; show more...; Sciortino, Franc ...; Schurtenberger, ...; show less...

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Chemical Science ...; and Physical Chemist ...

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