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Measuring forces between protein fibers by microscopy

By C. W. (Christopher W.) Jones, J. C. Wang, R. W. Briehl and Matthew S. Taylor

Abstract

We propose a general scheme for measuring the attraction between mechanically frustrated semiflexible fibers by measuring their thermal fluctuations and shape. We apply this analysis to a system of sickle hemoglobin (HbS) fibers that laterally attract one another. These fibers appear to “zip” together before reaching mechanical equilibrium due to the existence of cross-links into a dilute fiber network. We are also able to estimate the rigidities of the fibers. These rigidities are found to be consistent with sickle hemoglobin “single” fibers 20 nm in diameter, despite recent experiments indicating that fiber bundling sometimes occurs. Our estimate of the magnitude of the interfiber attraction for HbS fibers is in the range 8 ± 7 kBT/μm, or 4 ± 3 kBT/μm if the fibers are assumed, a priori to be single fibers (such an assumption is fully consistent with the data). This value is sufficient to bind the fibers, overcoming entropic effects, although extremely chemically weak. Our results are compared to models for the interfiber attraction that include depletion and van der Waals forces. This technique should also facilitate a similar analysis of other filamentous protein assembles in the future, including β-amyloid, actin, and tubulin

Topics: QR
Publisher: Biophysical Society
Year: 2005
OAI identifier: oai:wrap.warwick.ac.uk:909

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Citations

  1. (1993). Flexural rigidity of microtubules and actin filaments measured from thermal fluctuations in shape. doi
  2. (2002). Fluctuations in self-assembled sickle haemoglobin fibers. doi
  3. Force between Protein Fibers 2441 doi
  4. (1994). Fragility and structure of hemoglobin S fibers and gels and their consequences for gelation kinetics and rheology.
  5. (2003). Interactions between sickle hemoglobin fibers. Faraday Discuss. doi
  6. (2002). Micromechanics of isolated sickle cell hemoglobin fibers: bending moduli and persistence lengths. doi
  7. (1995). Nucleation, fiber growth and melting, and domain formation and structure in sickle cell hemoglobin gels.
  8. (1990). Sickle cell hemoglobin polymerization. doi
  9. (1998). Statistical Data Analysis. doi
  10. (1986). Theory of Elasticity. doi
  11. (2003). Twisted protein aggregates and disease: the stability of sickle hemoglobin fibers. doi

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