How is the structure of an alpha-helix maintained?
Miles or Hannah or Doc or whoever --
Be sure to post each question only once and post consistently in one name. Doubling up on everything doesn't help you, and it wastes everyone's time.
The structure of an alpha-helix is primarily maintained through intramolecular hydrogen bonds, which form between the oxygen atom of the peptide backbone carbonyl group and the hydrogen atom of the peptide backbone amino group. This hydrogen bonding occurs between every fourth amino acid along the alpha-helix. Here's how you can understand and visualize the structure of an alpha-helix:
1. Start with a polypeptide chain: Begin with a linear chain of amino acids that make up the peptide backbone.
2. Form a repeating pattern: Imagine bending the chain into a helical shape, with a right-handed spiral. This helical shape is the alpha-helix.
3. Identify hydrogen bonding pattern: The backbone oxygen of an amino acid will form a hydrogen bond with the backbone hydrogen of an amino acid located four positions away in the helix. For example, the oxygen of the first amino acid will bond with the hydrogen of the fifth amino acid, and so on. This repeating hydrogen bonding pattern stabilizes the helical structure.
4. Stabilize with side chain interactions: The side chains of the amino acids also contribute to the stability of the alpha-helix. For example, certain amino acids with bulky or charged side chains can participate in additional interactions, such as electrostatic attractions or hydrophobic interactions, which further stabilize the helix.
Overall, both the intramolecular hydrogen bonding between the backbone atoms and the interactions between the side chains help maintain the structure of the alpha-helix.