Table 1.

Mechanical parameters of A-tracts and control molecules obtained in this work. Mechanical parameters from AFM data were calculated from the fits to the data presented in Figure 2D and Supplementary Figure S5. Errors are the error of the fit. AFM imaging conditions are described in the Materials and Methods section. Mechanical parameters from MT and OT data are the average of the parameters obtained for each molecule and the errors are the standard deviation of the mean. For MT measurements,  and were obtained by fitting the data to Equation (7) in the F < 1 pN regime. For OT measurements,  and  were extracted by fitting the data to Equation (8) in the 1 pN < < 10 pN force range. and were calculated by fitting the OT data to Equation (9) in the 10–45 pN force range. N denotes the number of molecules

Atomic force microscopy
Imaging conditions	Molecule	(nm)	(nm)	(nm)	(μm−1)	# Traces
Air imaging Mg2+	A-tract	871 ± 27 (N = 43)	23 ± 1	55 ± 1	17 ± 1	178
	Control	898 ± 21 (N = 44)	54 ± 1			122
Air imaging Mg2+ & Ni2+	A-tract	889 ± 28 (N = 41)	24 ± 1	53 ± 1	17 ± 1	141
	Control	902 ± 24 (N = 38)	47 ± 1			89
Liquid imaging Mg2+ & Ni2+	A-tract	858 ± 46 (N = 40)	18 ± 4	47 ± 3	18 ± 1	180
	Control	886 ± 53 (N = 43)	50 ± 1			163
Magnetic tweezers
[NaCl] (mM)	Molecule	(nm)	(nm)	(nm)	(pN)	N
1	A-tract	1921 ± 31	22 ± 1			14
	Control	1945 ± 31	49 ± 1			15
10	A-tract	1910 ± 14	19 ± 1			25
	Control	1940 ± 22	45 ± 1			18
100	A-tract	1946 ± 16	15 ± 1			28
	Control	1866 ± 20	44 ± 1			20
500	A-tract	2039 ± 20	12 ± 1			29
	Control	1923 ± 19	41 ± 1			19
Optical tweezers
[NaCl] (mM)	Molecule	(nm)	(nm)	(nm)	(pN)	N
50	A-tract	1890 ± 7	20 ±1	38 ± 3	2560 ± 260	9
	Control	1833 ± 7	42 ± 2	49 ± 5	1680 ± 80	10
100	A-tract	1872 ± 16	20 ± 2	44 ± 3	2400 ± 220	15
	Control	1836 ± 3	42 ± 2	47 ± 4	1540 ± 90	17
500	A-tract	1839 ± 3	21 ± 1	37 ± 3	2390 ± 190	17
	Control	1830 ± 3	41 ± 3	49 ± 4	1560 ± 100	13