nonBDNA

nonBDNA is a term used to describe DNA that does not form the canonical B-form double helix. While the B-DNA structure is the most common and stable conformation of DNA under physiological conditions, DNA can adopt various other structural forms depending on factors like sequence, hydration, salt concentration, and the presence of proteins. These alternative structures include A-DNA, Z-DNA, and G-quadruplexes, among others.

A-DNA is a wider, shorter helix than B-DNA, often found under dehydrating conditions. Z-DNA is a left-handed helix with a zigzagging backbone, typically found in GC-rich sequences. G-quadruplexes are four-stranded structures formed by guanine-rich sequences.

The existence and biological significance of these non-canonical DNA structures are areas of active research. They are thought to play roles in gene regulation, DNA replication, and DNA repair. For instance, Z-DNA has been implicated in transcription and recombination. G-quadruplexes are found in telomeres and promoter regions and are potential targets for anticancer drugs. Understanding non-canonical DNA structures is crucial for a complete picture of DNA function and its involvement in cellular processes.