Introduction - This script shows the structure of A DNA. (Based on 116d.pdb, C.A. Bigman et al, J. Mol. Biol. 227 738 (1992)).
This is A DNA. One chain (YELLOW) runs 3' TO 5', while the other (GREEN) runs 5' TO 3' - They are antiparallel. A DNA has a very deep major groove and virtually no minor groove.
Here is the cross section of A DNA. Note the hole in the center.