Table 1.

Best-Fit Parameters and Reduced χ² of the Fits to the Fractional Elongation or the Fractional Untwisting at Zero Force or Zero Torque, Respectively

cNaCl (mM)	Model	Kd,0 (μM)	δEth (nm)	φEth	n	ω	Reduced χ2
140	noncooperative	8.4 ± 1.1	(0.34)	–	1.8 ± 0.1	–	13.0
		8.4 ± 1.2	–	26.5 ± 0.6°	(1.8)	–	9.2
	anticooperative	5.8 ± 0.4	0.33 ± 0.01	–	(1)	0.030 ± 0.003	1.4
		6.1 ± 0.6	–	25.9 ± 0.6°	(1)	0.025 ± 0.004	1.8
2000	noncooperative	61 ± 4	(0.34)	–	1.8 ± 0.1	–	9.3
		50 ± 2	–	28.3 ± 0.2°	(1.8)	–	6.7
	anticooperative	51 ± 2	0.34 ± 0.01	–	(1)	0.035 ± 0.004	0.71
		50 ± 2	–	30.6 ± 0.4°	(1)	0.010 ± 0.002	1.3

Errors were obtained from the covariance matrix of the corresponding fit. Best-fit curves are shown in Figs. 2b and 3b as well as Figs. S2a and S6a. Parameters in brackets were taken as fixed values.