Table 1 A-DNA structural lengths.

Relevant measured lengths of A-DNA, as obtained by imaging data reported in Fig. 1 (see inset), are shown. The data reported for HRTEM imaging are coherent and comparable with the x-ray accepted values (1315, 30) and the simulations shown in Fig. 2.

A-DNA structural
characteristics
HRTEM
measurements* (Å)
X-ray and
simulation data (Å)
Diameter21.223.0
Rise/base pair along axis2.52.6
Pitch/tum of helix26.528.2
Phosphate + sugar
(backbone A1)
5.15.3
Base (B1)3.64.0
Base (B2)5.25.4
Phosphate + sugar
(backbone A2)
5.05.3
Base length (B1 + B2 +
base interdistance)
11.311.5
Tilt of base pair relative
to the axis
19°19°

*The statistical error for the measured lengths is estimated to be 1.5 Å from the inset of Fig. 1.

†X-ray accepted values of relevant lengths as reported in (1315, 30).

‡Data obtained from the simulation of the twisted bases of Fig. 2 and as reported in (13).