An α-helix is a common structural motif in proteins, characterized by a right-handed coil or spiral conformation. It is stabilized by hydrogen bonds between the backbone atoms of amino acids in the polypeptide chain.
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The α-helix structure was first proposed by Linus Pauling and Robert Corey in 1951.
Each turn of an α-helix consists of approximately 3.6 amino acid residues.
The hydrogen bonds that stabilize the α-helix form between the carbonyl oxygen of one amino acid and the amide hydrogen four residues away.
α-helices are often found in the regions of proteins that span cell membranes, such as transmembrane helices.
The side chains (R groups) of amino acids in an α-helix extend outward from the helical backbone, allowing for interactions with other molecules or protein domains.
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Related terms
β-sheet: A secondary structure in proteins characterized by beta strands connected laterally by at least two or three backbone hydrogen bonds.
Hydrogen Bond: A weak bond between two molecules resulting from an electrostatic attraction between a proton in one molecule and an electronegative atom in another.