How many amino acids are present in a single turn of a-helix?
a-helix is a rod-like helical structure where peptide backbone wound around a long axis, the side chains (R groups) radiate outward N-H group of one amino acid is hydrogen bonded to the C=O group of the amino acid located four residues earlier along the protein sequence. This hydrogen bonding creates a right-handed spiral or helix (coiled, rod-like structure). Most of the naturally occurring a-helix are right-handed. One turn of a-helix contains 3.6 amino acids. Distance between two adjacent amino acids is 1.5 Adeg
3.3
3.6
10.5
11.5
Proteins bonds and structure