What is a key feature of Z-form DNA?

Z-form DNA is characterized by its left-handed helical structure, which distinguishes it from the more common right-handed forms of DNA (such as A-form and B-form). This unique orientation of the helical backbone contributes to the distinctive zigzag appearance of the molecule, hence the name "Z-form". The left-handed twist in Z-form DNA is stabilized by specific sequences of nucleotides, particularly those rich in cytosine and guanine.

While the stability of Z-form DNA in aqueous conditions is not typically greater than that of B-form DNA, it can be favored under specific conditions, such as high salt concentrations or particular sequence motifs. Z-form DNA is also noteworthy for its potential roles in biological processes, such as gene regulation and the formation of DNA structures under certain cellular conditions. However, it is not primarily associated with viral genomes, nor is it seen as the most stable form in all environments. Thus, identifying Z-form DNA as a left-handed helical form is crucial for understanding its unique properties and biological significance.