In molecular biology, the term double helix[1] refers to the structure formed by double-stranded molecules of nucleic acids such as DNA. The double helical structure of a nucleic acid complex arises as a consequence of its secondary structure, and is a fundamental component in determining its tertiary structure. The structure was discovered by Maurice Wilkins, Rosalind Franklin, her student Raymond Gosling, James Watson, and Francis Crick,[2] while the term "double helix" entered popular culture with the 1968 publication of Watson's The Double Helix: A Personal Account of the Discovery of the Structure of DNA.
The DNA double helix biopolymer of nucleic acid is held together by nucleotides which base pair together.[3] In B-DNA, the most common double helical structure found in nature, the double helix is right-handed with about 10–10.5 base pairs per turn.[4] The double helix structure of DNA contains a major groove and minor groove. In B-DNA the major groove is wider than the minor groove.[3] Given the difference in widths of the major groove and minor groove, many proteins which bind to B-DNA do so through the wider major groove.[5]