Review Article
Comparative Biomechanics of Thick Filaments and Thin Filaments with Functional Consequences for Muscle Contraction
Table 1
Mechanical properties of thick filaments and thin filaments.
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Measured values are listed in bold, along with the referenced study. Stiffness values represent the spring constant for a filament length (L) of 1000 m. To compare between measurements, the calculations for stiffness (k), Young’s modulus (E), and persistence length (Lp) required an estimate of filament geometry listed in the footnotes. Otherwise, E = kL/Ac, where Ac is cross-sectional area [13] and Lp = EI/kBT, where I is the second moment of inertia, kB is the Boltzman constant, and temperature (T) was 300 K [129]. lculations assumed a solid, cylindrical filament backbone of radius 6.5 nm for skeletal thick filaments [30] and 8 nm [130] for cardiac thick filaments. For insect flight muscle filaments, calculations assumed a hollow cylinder with an outer radius of 7.5 nm and an inner radius of 3 nm [131]. lculations for undecorated actin filaments assumed a solid, cylindrical filament backbone of radius 2.8 nm [13]. *In the presence of phalloidin. lculations for thin filaments and decorated actin filaments assumed a solid, cylindrical filament backbone of radius 4 nm [30]. Abbreviations: Tm: Tropomyosin; Cad: Caldesmon; Thin: Native thin filament; Thick: Native thick filament; AFM: Atomic force microscope; IFM: Indirect flight muscles. |