Micromechanical Thermal Assays of Ca2+-Regulated Thin-Filament Function and Modulation by Hypertrophic Cardiomyopathy Mutants of Human Cardiac Troponin
Figure 6
Temperature dependence of two apparent rate constants that may limit actin filament sliding speed at pCa 5. Data in Figure 3 ( < ~54°C) for sliding speed of regulated thin filaments were fitted to (2). The inverse of each of the exponential rate terms in the denominator of (2) is plotted: for WT regulated thin filaments, one rate exhibits only slight temperature sensitivity (solid black line) while the other is markedly temperature sensitive (red line). The rate-limiting step for filament sliding is the smaller of the two rates, and is the intersection of the two lines. The less temperature sensitive rate is also shown for unregulated F-actin (dashed black line; data from Figure 3). Note that by assuming the temperature-sensitive rate (red line) is similar for both instances, decreasing the less temperature sensitive rate (black arrow, as observed experimentally with unregulated F-actin) decreases .
