If a cis peptide bond is found in a protein, the most likely amino acid to contribute the amine to the amide bond is ______.
A)phenylalanine
B)leucine
C)proline
D)glycine
E)arginine

Question

Quizplus · Accepted Answer

Proline is the only amino acid that can form a cis peptide bond due to its unique structural characteristic of having its side chain bonded to both the amine and carbonyl groups of the amino acid backbone. This results in a rigid ring structure that is unable to rotate, allowing the amide bond to adopt a cis conformation more easily.

If a Cis Peptide Bond Is Found in a Protein