A helical wheel is a type of

plot Plot or Plotting may refer to: Art, media and entertainment * Plot (narrative), the story of a piece of fiction Music * ''The Plot'' (album), a 1976 album by jazz trumpeter Enrico Rava * The Plot (band), a band formed in 2003 Other * ''Plot ...

or visual representation used to illustrate the properties of

alpha helices 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 the amino acid located four residues earli ...

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respon ...

s. The

sequence In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of elements (possibly infinite) is called ...

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...

s that make up a helical region of the protein's

secondary structure Protein secondary structure is the three dimensional form of ''local segments'' of proteins. The two most common secondary structural elements are alpha helices and beta sheets, though beta turns and omega loops occur as well. Secondary struct ...

are plotted in a rotating manner where the angle of rotation between consecutive amino acids is 100°, so that the final representation looks down the helical axis.

Polarity and Characteristics

The plot reveals whether

hydrophobic In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, ...

amino acids are concentrated on one side of the helix, usually with

polar Polar may refer to: Geography Polar may refer to: * Geographical pole, either of two fixed points on the surface of a rotating body or planet, at 90 degrees from the equator, based on the axis around which a body rotates *Polar climate, the cli ...

hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are ...

amino acids on the other. This arrangement is common in

within

globular protein In biochemistry, globular proteins or spheroproteins are spherical ("globe-like") proteins and are one of the common protein types (the others being fibrous, disordered and membrane proteins). Globular proteins are somewhat water-soluble (fo ...

s, where one face of the helix is oriented toward the

hydrophobic core The hydrophobic effect is the observed tendency of nonpolar substances to aggregate in an aqueous solution and exclude water molecules. The word hydrophobic literally means "water-fearing", and it describes the segregation of water and nonpola ...

and one face is oriented toward the

solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...

-exposed surface. Specific patterns characteristic of

protein fold A protein superfamily is the largest grouping ( clade) of proteins for which common ancestry can be inferred (see homology). Usually this common ancestry is inferred from structural alignment and mechanistic similarity, even if no sequence similar ...

s and protein docking motifs are also revealed, as in the identification of

leucine zipper A leucine zipper (or leucine scissors) is a common three-dimensional structural motif in proteins. They were first described by Landschulz and collaborators in 1988 when they found that an enhancer binding protein had a very characteristic 30-ami ...

dimerization regions and

coiled coil A coiled coil is a structural motif in proteins in which 2–7 alpha-helices are coiled together like the strands of a rope. ( Dimers and trimers are the most common types.) Many coiled coil-type proteins are involved in important biological f ...

s. This projection diagram is often called and "Edmundson wheel" after its inventor.

Drawing Helical Wheels

Helical wheels can be drawn by a variety of software packages includin
helixvis
in R
heliquest
in R, or via the HELIQUEST server.

References

External links

Less traditional, more colorful wheels
(requires Macromedia Flash)
DrawCoil 1.0

Helical Wheel Projections, UC Riverside

NetWheels, High quality Helical Wheel and Net projections

High-quality helical wheels in R
Protein structure Protein methods Amino acids {{biochem-stub

Polarity and Characteristics

Drawing Helical Wheels

References

Further reading

External links