Which are true describing the secondary structure of a protein that is an $\alpha$-helix?
I. The helix is coiled counterclockwise.
II. The N-H bond and the C=O bond point outward.
III. Hydrogen bonding is between groups 4 amino acid units apart.
IV. The coil has 3.6 amino acids per turn.

Question

Quizplus · Accepted Answer

III and IV are true for the α-helix structure of proteins. In an α-helix, hydrogen bonds form between the carbonyl oxygen of one amino acid and the amide hydrogen of another, specifically four residues away. This structure results in 3.6 amino acids per turn, not in the N-H and C=O bonds pointing outward or the helix coiling counterclockwise.

Which Are True Describing the Secondary Structure of a Protein α\alphaα

Which Are True Describing the Secondary Structure of a Protein $\alpha$