Left-Handed Z-Dna

Left-Handed Z-Dna

 Alternating runs of (CG)n•(CG)n or (TG)n•(CA)n dinucleotides in DNA, under superhelical tension or high salt (more than 3 M NaCl) (M, moles per liter) can adopt a left-handed helix called Z-DNA. In this form, the two DNA strands become wrapped in a left-handed helix, which is the opposite sense to that of canonical B-DNA. This can occur within a small region of a larger right-handed B-DNA molecule, creating two junctions at the B-Z transition region.