Interactions between planar grafted neurofilament side-arms

Mark J. Stevens, Jan H. Hoh

Research output: Contribution to journalArticle

Abstract

The side-arms of neurofilaments (NFs) have been proposed to be highly disordered, leading to an entropically and electrostatically based repulsion that modulates interfilament spacing. To characterize the behavior of two interacting polymer brushes in a system of this type, we performed molecular dynamics simulations of neurofilament brushes using a four bead reduced amino acid set coarse-grained model. In these simulations, we examined components of the neurofilament brush, NF-L, NF-M, and phosphorylated NF-H (NF-HP), individually. Each protein type was grafted to planar surfaces and simulations were performed for a range of separations of two apposed grafted surfaces. The calculated force-separation curves show the force increases as the reciprocal separation as predicted for polyelectrolyte brushes at high salt. All three systems can be overlapped on a single force-separation curve, which is not expected given the variation in amino acid sequence and charges on the polymers. Examination of structural properties shows scaling behavior in the average brush height, end-to-end distance, and the density interpenetration. Some of this scaling can be understood in terms of treating the NF proteins as effective polyelectrolytes, but some cannot suggesting a distinct polyampholyte behavior. Correlations are found between oppositely charged residues in opposite brushes. However, these correlations are weak in comparison to the strong correlations within each brush. In comparison with recent experimental data that observes condensed and expanded gel states, our results suggest that the condensed state structure involves significant interdigitation of the side-arms.

Original languageEnglish (US)
Pages (from-to)7541-7549
Number of pages9
JournalJournal of Physical Chemistry B
Volume115
Issue number23
DOIs
StatePublished - Jun 16 2011

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brushes
Brushes
interactions
Polyelectrolytes
amino acids
Amino acids
Polymers
proteins
Proteins
Neurofilament Proteins
scaling
Amino Acids
simulation
polymers
curves
beads
Molecular dynamics
Structural properties
Gels
Salts

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Materials Chemistry
  • Surfaces, Coatings and Films

Cite this

Interactions between planar grafted neurofilament side-arms. / Stevens, Mark J.; Hoh, Jan H.

In: Journal of Physical Chemistry B, Vol. 115, No. 23, 16.06.2011, p. 7541-7549.

Research output: Contribution to journalArticle

Stevens, Mark J. ; Hoh, Jan H. / Interactions between planar grafted neurofilament side-arms. In: Journal of Physical Chemistry B. 2011 ; Vol. 115, No. 23. pp. 7541-7549.
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