An alternative notation for a polypeptide helix is to list t

An alternative notation for a polypeptide helix is to list the number of residues per turn and the number of atoms found in the hydrogen-bonded loop that connects adjacent backbone atoms.

For example, a 310 helix contains 3 amino acids per turn and uses an i to i + 3 hydrogen-bonding pattern in which the H-bonded loop has 10 atoms.

For a polypeptide composed of g-amino acids, state the nomenclature of a helix with the same H-bonding pattern and number of residues per turn as a 310 helix.

PLEASE SHOW WORK, thank you so much for your help!

Solution

The alpha helices can be described as 3.6₁₃ helix where i + 4 spacing adds 3 more atoms to the H bonded loop compared to the tighter 3₁₀ helix and on average 3.6 amino acid are involved in one ring of alpha helix. The subscripts refer to the number of atoms in the closed loop formed by the hydrogen bond.

For a polypeptide with g amino acids, the nomenclature would be

g to g + 3 hydrogen bonding pattern having a 3₁₀ helix.