  In this work we report the study of conformation dependent electronic
transport properties of DNA double-helix within tight-binding framework
including its helical symmetry. We have studied the changes in localization
properties of DNA as we alter the number of stacked bases within a pitch of the
double-helix keeping the total number of nucleotides in the DNA chain fixed. We
take three DNA sequences, two of them are periodic and one is random and
observe that localization length increases as we increase the radius of DNA
double-helix i.e., number of nucleotides within a pitch. We have also
investigated the effect of backbone energetic on the I-V response of the system
and we find that in presence of helical symmetry, depending on the interplay of
conformal variation and disorder strength DNA can be found in either metallic
or semiconducting and even in an insulating phase, which in turn successfully
explain all the experimental findings by a single model.
