Concept #1: Phi, Psi & Omega Bonds

Practice: Which of the following pairs of peptide-backbone bonds show free rotation around both bonds?

Concept #2: Ramachandran Plot

Practice: A Ramachandran plot shows:

Practice: Why are some regions of a Ramachandran plot shaded while others are unshaded? Circle all true answers.

Practice: The predominate structure in α-keratin, a mammalian protein that makes up large portions of hair & nails, is the α-helix. Mark the approximate locations on a Ramachandran plot you might expect to find φ and ψ angles for α-keratin amino acid residues.

Practice: The principal component of silk is the protein fibroin, which is a classic example of β-sheet structure. Mark the approximate locations on a Ramachandran plot you might expect to find φ and ψ angles for silk amino acid residues.

Practice: Which of the following statements is true for the portion of the peptide shown in the figure below?