Journal of Biophysics / 2009 / Article / Tab 4

Research Article

Tropomyosin Period 3 Is Essential for Enhancement of Isometric Tension in Thin Filament-Reconstituted Bovine Myocardium

Table 4

Measured parameters of Cross-bridges. *P value ≤ .05 compared to nfTm; **P value ≤.01 compared to nfTm; else, P value > .05. Other than rigor stiffness, all parameters were measured in the standard activating solution. is the steady-state active tension. Tension and stiffness were normalized against the actin filament tension in the standard activating solution at 25°C ( = 9.0 ± 0.9 kPa, ±SEM, N = 52). To deduce , 5 frequency points around the minimum are fitted to the cubic equation with 4 constants. corresponds to the rate constant of phase 3, and corresponds to that of phase 2 of step analysis [32]. In all experiments, temperature was 25°C, ionic strength 200 mM, and pH 7.00. The rigor stiffness was measured at 100 Hz. The data were individually fitted to respective equations, averaged, and tabulated with ±SEM. Data based on Lu et al. [13].

nfTm Acetyl TmUnits

Number of expts.1517189
Tension ( )1.51 ± 0.281.65 ± 0.290.91 ± 0.0 1.65 ± 0.24
103 ± 24103 ± 1471 ± 589 ± 14
1.56 ± 0.081.58 ± 0.141.31 ± 0.1 1.91 ± 0.1
Rigor stiffness166 ± 11201 ± 1 249 ± 59159 ± 23
8.6 ± 0.47.4 ± 0.47.2 ± 0. 7.6 ± 0.6
6.2 ± 0.46.3 ± 0.54.7 ± 0. 7.1 ± 1.0
28 ± 128 ± 236 ± 41 ±
49 ± 1151 ± 934 ± 428 ±
56 ± 2055 ± 1322 ± 29 ± 6
110 ± 34107 ± 1758 ± 390 ± 13

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