α-helix
Definition
An α-helix is a common structural motif in proteins, characterized by a right-handed coiled or spiral conformation. It is stabilized by hydrogen bonds between the backbone atoms of the amino acids.
5 Must Know Facts For Your Next Test
- The α-helix structure was first proposed by Linus Pauling in 1951.
- It typically consists of 3.6 amino acids per turn of the helix.
- The hydrogen bonds occur between the carbonyl oxygen of one amino acid and the amide hydrogen of another four residues earlier.
- α-helices are often found in the hydrophobic core of globular proteins.
- They can be disrupted by proline residues, which introduce kinks in the helical structure.
Review Questions
- What type of bond stabilizes an α-helix?
- How many amino acids are there per turn in an α-helix?
- Why do proline residues disrupt α-helices?
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Related terms
β-sheet: A secondary protein structure 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 the other.
Secondary Structure: The local folded structures that form within a polypeptide due to interactions between atoms of the backbone.
