Alpha helix

An alpha helix (or α-helix) is a sequence of amino acids in a protein that are twisted into a coil (a helix).

The alpha helix is the most common structural arrangement in the secondary structure of proteins. It is also the most extreme type of local structure, and it is the local structure that is most easily predicted from a sequence of amino acids.

The alpha helix has a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid that is four residues earlier in the protein sequence.