Alpha_helix A common motif in the secondary structure of proteins, the alpha helix (α-helix) is a right- or left-handed coiled conformation, resembling a spring, in which every backbone N-H group donates a hydrogen bond to the backbone C=O group of the amino acid four residues earlier ( hydrogen bonding). This secondary structure is also sometimes called a classic Pauling-Corey-Branson alpha helix (see below). (See also helix.)