The alpha helix (-helix)

The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid located four residues earlier along the protein sequence. The alpha helix is also called a classic Pauling–Corey–Branson α-helix. The name is also used for this type of helix, denoting the average number of residues per helical turn, with 13 atoms being involved in the ring formed by the hydrogen bond. Among types of local structure in proteins, the α-helix is the most extreme and the most predictable from sequence, as well as the most prevalent. ----------------------------------------------------------------------------- A specific protein has an 18-residue long α-helix with the following sequence: PENQWKQELDTRYRNALQ A) How many full turns are in this α-helix? B) What is the length of the helix (in Angströms) in the direction of the helix axis? #TheAlphaHelix #helix #aminoAcid #polypeptide #protein #proteinFolding