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Alpha helix secondary structure

The peptide backbone twists forming a helix with the amino acid sidechains protruding outwards.

(to simplify, H atoms are not shown)

The helix can be seen better if we draw just a line that joins the alpha carbons.

Let's show again the bonds in the backbone, still with hidden sidechains: .

(move the molecule and you will perceive the helical shape)

The helix is stabilized by hydrogen bonds (••••••) between the carbonyl groups and the nitrogens in the peptide bonds.

>C=O••••••H–N<

Axial view (from the end).
Observe that the helix turns to the right (it is right-handed), as the thread in a screw.

Show sidechains.

Each amino acid in its own color:
Ser- Glu- Ala-Ala- Ile- Asn- Arg- Gln- Ile- Asn- Leu- Glu- Leu- Tyr- Ala

In models for large proteins, the portions with alpha helix conformation are usually rendered in a simplified “cartoon” form as a spiral ribbon , or as a cylinder .