The peptide bond
A) is most stable in the cis configuration.
B) has a mix of single and double bond characters.
C) can rotate around the carbonyl and N bond but not around the $\alpha$-carbon and N bond.
D) can function as a weak acid and weak base.

Question

Quizplus · Accepted Answer

The peptide bond has partial double bond character due to resonance between the carbonyl group and the nitrogen atom, which restricts rotation around the bond. However, rotation is possible around the adjacent alpha carbon-nitrogen bond. The stability of cis/trans isomers of the peptide bond is dependent on the size of the R-groups on either side of the bond. The peptide bond itself does not function as an acid or base, but can participate in acid-base reactions due to the presence of the nitrogen and carbonyl groups on either side.

The Peptide Bond A) Is Most Stable in the Cis α\alphaα

The Peptide Bond
A) Is Most Stable in the Cis $\alpha$