Unconventional salt trend from soft to stiff in single neurofilament biopolymers

Roy Beck, Joanna Deek, Myung Chul Choi, Taiji Ikawa, Osamu Watanabe, Erwin Frey, Philip Pincus, Cyrus R. Safinya

Research output: Contribution to journalArticlepeer-review


We present persistence length measurements on neurofilaments (NFs), an intermediate filament with protruding side arms, of the neuronal cytoskeleton. Tapping mode atomic force microscopy enabled us to visualize and trace at subpixel resolution photoimmobilized NFs, assembled at various subunit protein ratios, thereby modifying the side-arm length and chain density charge distribution. We show that specific polyampholyte sequences of the side arms can form salt-switchable intrafilament attractions that compete with the net electrostatic and steric repulsion and can reduce the total persistence length by half. The results are in agreement with present X-ray and microscopy data yet present a theoretical challenge for polyampholyte interchain interactions.

Original languageEnglish
Pages (from-to)18595-18599
Number of pages5
Issue number24
StatePublished - 21 Dec 2010


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