Category: Helices

Triple helix
In the fields of geometry and biochemistry, a triple helix (plural triple helices) is a set of three congruent geometrical helices with the same axis, differing by a translation along the axis. This m
Boerdijk–Coxeter helix
The Boerdijk–Coxeter helix, named after H. S. M. Coxeter and , is a linear stacking of regular tetrahedra, arranged so that the edges of the complex that belong to only one tetrahedron form three inte
Deoxyribonucleic acid (/diːˈɒksɪˌraɪboʊnjuːˌkliːɪk, -ˌkleɪ-/; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic in
Obsolete models of DNA structure
In addition to the variety of verified DNA structures, there have been a range of proposed DNA models that have either been disproven, or lack evidence. Some of these structures were proposed during t
Tendril perversion
Tendril perversion is a geometric phenomenon sometimes observed in helical structures in which the direction of the helix transitions between left-handed and right-handed. Such a reversal of chirality
Xeno nucleic acid
Xeno nucleic acids (XNA) are synthetic nucleic acid analogues that have a different sugar backbone than the natural nucleic acids DNA and RNA. As of 2011, at least six types of synthetic sugars have b
DNA supercoil
DNA supercoiling refers to the amount of twist in a particular DNA strand, which determines the amount of strain on it. A given strand may be "positively supercoiled" or "negatively supercoiled" (more
Beta helix
A beta helix is a tandem protein repeat structure formed by the association of parallel beta strands in a helical pattern with either two or three faces. The beta helix is a type of solenoid protein d
Nucleic acid double helix
In molecular biology, the term double helix 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
Collagen helix
In molecular biology, the collagen triple helix or type-2 helix is the main secondary structure of various types of fibrous collagen, including type I collagen. In 1954, Ramachandran & Kartha (13, 14)
Gamma helix
Gamma helix (or γ-helix) is a type of secondary structure in proteins that has been predicted by Pauling, Corey, and Branson, but has never been observed in natural proteins. The hydrogen bond in this
Polyproline helix
A polyproline helix is a type of protein secondary structure which occurs in proteins comprising repeating proline residues. A left-handed polyproline II helix (PPII, poly-Pro II) is formed when seque
TMPad (the TransMembrane Protein Helix-Packing Database) is a repository of helix-helix interactions in membrane proteins
Hachimoji DNA
Hachimoji DNA (from Japanese 八文字 hachimoji, "eight letters") is a synthetic nucleic acid analog that uses four synthetic nucleotides in addition to the four present in the natural nucleic acids, DNA a
A superhelix is a molecular structure in which a helix is itself coiled into a helix. This is significant to both proteins and genetic material, such as overwound circular DNA. The earliest significan
A helix (/ˈhiːlɪks/) is a shape like a corkscrew or spiral staircase. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as th
Needle Tower
Needle Tower is a public artwork by American sculptor Kenneth Snelson located outside of the Hirshhorn Museum and Sculpture Garden in Washington, D.C., United States.
Non-B database
Non-B DB is a database integrating annotations and analysis of non-B DNA-forming sequence motifs. The database provides alternative DNA structure predictions including Z-DNA motifs, quadruplex-forming
310 helix
A 310 helix is a type of secondary structure found in proteins and polypeptides. Of the numerous protein secondary structures present, the 310-helix is the fourth most common type observed; following
Pi helix
A pi helix (or π-helix) is a type of secondary structure found in proteins. Discovered by crystallographer Barbara Low in 1952 and once thought to be rare, short π-helices are found in 15% of known pr
A hemihelix is a curved geometric shape consisting of a series of helices with alternating chirality, connected by a perversion at the reversals. The formation of hemihelices with periodic distributio
Alpha helix
The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of
Helical antenna
A helical antenna is an antenna consisting of one or more conducting wires wound in the form of a helix. A helical antenna made of one helical wire, the most common type, is called monofilar, while an