Α-helix

Common secondary structure of proteins

Template:Infobox protein structure An α-helix (alpha helix) is a common secondary structure of proteins and is a right-handed coiled or spiral conformation. It is a major structural motif in proteins and is characterized by a specific pattern of hydrogen bonding between the backbone amide and carbonyl groups of the peptide bond.

Structure

The α-helix is stabilized by hydrogen bonds between the N-H group of one amino acid and the C=O group of another amino acid four residues earlier. This results in a helical structure with 3.6 amino acids per turn and a pitch of 5.4 Å. The side chains of the amino acids in an α-helix extend outward from the helical backbone.

Discovery

The α-helix was first proposed by Linus Pauling, Robert Corey, and Herman Branson in 1951 as part of their work on the structure of proteins. Their model was based on X-ray crystallography data and chemical principles.

Function

α-helices are a fundamental component of the tertiary structure of proteins and play a crucial role in the function of many proteins. They can form coiled-coil structures, transmembrane helices, and are involved in the binding of ligands and substrates.

Examples

Many proteins contain α-helices, including hemoglobin, myoglobin, and keratin. The α-helix is also a key structural element in DNA-binding proteins and membrane proteins.

Related Structures

Other common secondary structures in proteins include the β-sheet and the β-turn. These structures, along with the α-helix, contribute to the overall folding and stability of proteins.

See Also

• Protein structure
• Secondary structure
• Tertiary structure
• Quaternary structure
• Hydrogen bond
• Peptide bond
• Linus Pauling
• X-ray crystallography