Alpha helix
Type of secondary structure of proteins / From Wikipedia, the free encyclopedia
An alpha helix (or α-helix) is a sequence of amino acids in a protein that are twisted into a coil (a helix).
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/c/ca/Polypeptide_forming_an_alpha_helix%2C_with_hydrogen_bonds_in_magenta.gif)
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-handed 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.