Correction for temperature-dependent effects of solvent viscosity (solid, cyan lines) on filament sliding speed of regulated thin filaments (solid symbols) and unregulated F-actin (open symbols). Data from Figure 1(c) were replotted in Arrhenius form (symbols as in Figure 1), with data omitted for regulated thin filaments above ∼54°C and filament sliding speeds expressed in μm s−1. Dashed lines (black) are linear least squares regressions on the data before correction for temperature-dependent changes in solvent viscosity. Note the change in slope at ∼38°C (Tt) for regulated thin filaments. Effects of temperature-dependent changes in solvent viscosity (normalized to that at body temperature, 37°C) were removed by assuming that speed varies inversely with viscosity, as demonstrated experimentally [43]; the net result of this correction in all instances is a decrease in apparent Ea.
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