Table 2.

Ca²⁺ dependence of troponin C orientation parameters

	C helix; TnC-BR55-62			E helix; TnC-BR95-102
	5 mm MgATP (n= 5)	5 mm MgATP + 25 μm blebbistatin (n= 4)	0 mm MgATP, rigor (n= 5)	5 mm MgATP (n= 5)	5 mm MgATP + 25 μm blebbistatin (n= 4)	0 mm MgATP, rigor (n= 4)
θf (deg)
1 nm[Ca2+]	52.3 ± 0.2	52.2 ± 0.2 ns	54.8 ± 0.1 *	46.3 ± 0.2	45.5 ± 0.1	54.4 ± 0.4
Maximal [Ca2+]	57.4 ± 0.2	57.0 ± 0.2 *	57.9 ± 0.1 *	50.0 ± 0.3	48.4 ± 0.2	56.9 ± 0.4
First Hill fit
Amplitude (deg)	5.04 ± 0.12	4.81 ± 0.05	1.12 ± 0.27	4.29 ± 0.34	3.70 ± 0.26	0.95 ± 0.20
EC50 (μm)	6.01 ± 0.54	7.29 ± 0.71 *	4.83 ± 0.44	4.60 ± 0.50	7.39 ± 1.00	4.37 ± 0.45
nH	3.01 ± 0.13	2.86 ± 0.27 ns	2.24 ± 0.33	3.06 ± 0.32	2.85 ± 0.13	2.21 ± 0.64
Second Hill fit
Amplitude (deg)	—	—	1.97 ± 0.20	—	—	1.59 ± 0.18
EC50 (μm)	—	—	0.28 ± 0.08	—	—	0.25 ± 0.05
nH	—	—	1.05 ± 0.12	—	—	0.73 ± 0.04
σg (deg)
1 nm[Ca2+]	24.3 ± 0.4	24.9 ± 0.2	27.4 ± 1.3	22.9 ± 0.4	23.4 ± 0.5	30.2 ± 2.2
Maximal [Ca2+]	24.8 ± 0.6	25.1 ± 0.3	26.0 ± 1.1	22.6 ± 0.6	22.5 ± 0.5	30.8 ± 2.8

Mean ±s.e.m. Comparison: paired t test, two-tailed; ^nsP > 0.05;

^*P < 0.05.