One of several forms that can be assumed by a DNA double helix. A-DNA is stable in dehydrated conditions. This form is less common than the dominant form found under physiological conditions -- Β-DNA. This form is also assumed by DNA-RNA hybrid helices and by regions of double-stranded RNA. It is a right-handed helix and is a more compact form than Β-DNA.
From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.