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Photo Mikael Lund

Mikael Lund

Professor

Photo Mikael Lund

Concentration-Induced Association in a Protein System Caused by a Highly Directional Patch Attraction

Author

  • Weimin Li
  • Björn A. Persson
  • Mikael Lund
  • Johan Bergenholtz
  • Malin Zackrisson

Summary, in English

Self-association of the protein lactoferrin is studied in solution using small-angle X-ray scattering techniques. Effective static structure factors have been shown to exhibit either a monotonic or a nonmonotonic dependence on protein concentration in the small wavevector limit, depending on salt concentration. The behavior correlates with a nonmonotonic dependence of the second virial coefficient on salt concentration, such that a maximum appears in the structure factor at a low protein concentration when the second virial coefficient is negative and close to a minimum. The results are interpreted in terms of an integral equation theory with explicit dimers, formulated by Wertheim, which provides a consistent framework able to explain the behavior in terms of a monomer-dimer equilibrium that appears because of a highly directional patch attraction. Short attraction ranges preclude trimer formation, which explains why the protein system behaves as if it were subject to a concentration-dependent isotropic protein-protein attraction. Superimposing an isotropic interaction, comprising screened Coulomb repulsion and van der Waals attraction, on the patch attraction allows for a semiquantitative modeling of the complete transition pathway from monomers in the dilute limit to monomer-dimer systems at somewhat higher protein concentrations.

Department/s

  • Physical Chemistry
  • Computational Chemistry
  • eSSENCE: The e-Science Collaboration

Publishing year

2016-09-01

Language

English

Pages

8953-8959

Publication/Series

Journal of Physical Chemistry B

Volume

120

Issue

34

Document type

Journal article

Publisher

The American Chemical Society (ACS)

Topic

  • Physical Chemistry (including Surface- and Colloid Chemistry)

Status

Published

ISBN/ISSN/Other

  • ISSN: 1520-6106