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 the amino acid located four residues earlier along the protein sequence.

Three-dimensional structure of an alpha helix in the protein crambin

The alpha helix is also called a classic Pauling–Corey–Branson α-helix. The name 3.613-helix is also used for this type of helix, denoting the average number of residues per helical turn, with 13 atoms being involved in the ring formed by the hydrogen bond.

Among types of local structure in proteins, the α-helix is the most extreme and the most predictable from sequence, as well as the most prevalent.

The image above contains clickable links
Interactive diagram of hydrogen bonds in protein secondary structure. Cartoon above, atoms below with nitrogen in blue, oxygen in red (PDB: 1AXC​)

Share this article:

This article uses material from the Wikipedia article Alpha helix, and is written by contributors. Text is available under a CC BY-SA 4.0 International License; additional terms may apply. Images, videos and audio are available under their respective licenses.