Alpha helix
Each section containing one of each of these groups is called a residue, a general term for a small part of a molecule. Each amine group forms a hydrogen bond with the carbonyl group four residues earlier. A prion is a protein that causes disease by changing the shape of another protein. It does this by changing some of the alpha helices, which are more common in normal cells, to beta sheets, which are more common in prions. The alpa helix consits of 3.6 residues per turn. All hydrogen bonds face in the same direction. If two or more alpha helices come together, they become a tertiary structure.