Table 3.

Average helical and base pair parameters of 10 best A4 structures

Local helical parameters					Base pair parameters
Base pair step	Roll, °	Tilt, °	Twist, °	Slide, Å	Base pair	Buckle, °	Propeller twist, °
G1-G2	4.7  ± 1.9	−2.0  ± 0.9	32.5  ± 1.3	−0.32  ± 0.34	G1⋅C20	4.1  ± 4.8	1.0  ± 4.1
G2-C3	−2.9  ± 0.7	2.2  ± 0.6	42.1  ± 0.6	−0.21  ± 0.16	G2⋅C19	11.5  ± 3.2	−0.8  ± 1.6
C3-A4	4.5  ± 0.9	4.6  ± 0.7	30.0  ± 0.7	−0.78  ± 0.23	C3⋅G18	−0.4  ± 2.0	−6.1  ± 1.6
A4-A5	−3.9  ± 1.0	−5.5  ± 0.2	35.3  ± 0.5	−0.48  ± 0.16	A4⋅T17	12.0  ± 1.6	−11.5  ± 2.1
A5-A6	0.0  ± 1.1	4.2  ± 0.2	40.3  ± 0.6	−1.29  ± 0.24	A5⋅T16	19.2  ± 1.0	−6.3  ± 1.1
A6-A7	−6.0  ± 0.5	2.2  ± 0.2	39.5  ± 0.2	0.61  ± 0.04	A6⋅T15	15.8  ± 0.5	−9.4  ± 0.6
A7-C8	−1.7  ± 0.7	−4.6  ± 0.3	38.7  ± 0.9	−0.85  ± 0.22	A7⋅T14	15.2  ± 0.7	−17.3  ± 0.5
C8-G9	0.4  ± 2.8	4.6  ± 0.5	38.9  ± 1.3	−0.20  ± 0.41	C8⋅G13	−9.4  ± 0.6	−12.3  ± 1.6
G9-G10	5.9  ± 2.3	−2.0  ± 1.7	37.3  ± 1.3	−0.03  ± 0.57	G9⋅C12	−11.9  ± 3.2	1.2  ± 6.0
					G10⋅C11	−22.4  ± 1.4	−7.1  ± 1.3

Calculated with 3DNA. A-tract parameters are shown in bold. Errors represent standard deviations of the mean.