Biochemistry Questions / Explore the role of peptide bonds in proteins. Why are peptide bonds considered planar, and how does the hybridization of Cα affect the flexibility of the peptide backbone?

Peptide bonds are between the c-terminal of one amino acid and the n-terminal of the neighbouring one. These C-N bonds have a partial double bond character, suggesting the N is sp2 hybridised. This prevents rotation through the bond, allowing the protein to fold correctly.

However, as there is not a pi bond on the C-N peptide bond, it can be considered planar. This is because only a sigma bond is present.