Can you please answer this question?
Identify the correct statement:
The phi and psi angles of a peptide bond describe rotation about the C-N bond of the O=C-NH peptide bond amide group.
The phi and psi angles describe the contribution of resonance to a peptide bond.
The type of secondary structure in a protein sequence can be estimated by the phi and psi angles for all alpha-carbons in a protein sequence.
Resonance stabilization of peptide bonds only occurs when the amino acid side chain is aromatic.