Question

How many amino acid residues are there in per turn of α-helix?

(a) 3.6

(b) 4.6

(c) 3.0

(d) 2.5

I have been asked this question during a job interview.

This interesting question is from Amino Acids and Proteins topic in portion Biomolecules and Catalysis of Life Sciences

Answer 1

Right answer is (a) 3.6

Easy explanation: Length of α-helix is usually 10-15 amino acid residue and there are 3.6 amino acid residues per turn of the helix. A single turn of α-helix has 13 atoms due to this α-helix is also referred as 3.613 helix.