The self-assembly, elasticity, and dynamics of cardiac thin filaments

Tassieri, M. , Evans, R.M.L., Barbu-Tudoran, L., Trinick, J. and Waigh, T.A. (2008) The self-assembly, elasticity, and dynamics of cardiac thin filaments. Biophysical Journal, 94(6), pp. 2170-2178. (doi:10.1529/biophysj.107.116087)

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Publisher's URL: http://dx.doi.org/10.1529/biophysj.107.116087

Abstract

Solutions of intact cardiac thin filaments were examined with transmission electron microscopy, dynamic light scattering (DLS), and particle-tracking microrheology. The filaments self-assembled in solution with a bell-shaped distribution of contour lengths that contained a population of filaments of much greater length than the in vivo sarcomere size (∼1 μm) due to a one-dimensional annealing process. Dynamic semiflexible modes were found in DLS measurements at fast timescales (12.5 ns–0.0001 s). The bending modulus of the fibers is found to be in the range 4.5–16 × 10−27 Jm and is weakly dependent on calcium concentration (with Ca2+ ≥ without Ca2+). Good quantitative agreement was found for the values of the fiber diameter calculated from transmission electron microscopy and from the initial decay of DLS correlation functions: 9.9 nm and 9.7 nm with and without Ca2+, respectively. In contrast, at slower timescales and high polymer concentrations, microrheology indicates that the cardiac filaments act as short rods in solution according to the predictions of the Doi-Edwards chopsticks model (viscosity, η ∼c3, where c is the polymer concentration). This differs from the semiflexible behavior of long synthetic actin filaments at comparable polymer concentrations and timescales (elastic shear modulus, G′ ∼ c1.4, tightly entangled) and is due to the relative ratio of the contour lengths (∼30). The scaling dependence of the elastic shear modulus on the frequency (ω) for cardiac thin filaments is G′ ∼ω3/4 ± 0.03, which is thought to arise from flexural modes of the filaments.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Tassieri, Dr Manlio
Authors: Tassieri, M., Evans, R.M.L., Barbu-Tudoran, L., Trinick, J., and Waigh, T.A.
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
College of Science and Engineering > School of Engineering > Biomedical Engineering
Journal Name:Biophysical Journal
Publisher:Elsevier
ISSN:0006-3495
Published Online:12 November 2008

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