Chapter 17.8, Problem 19P

Interpretation Introduction

Interpretation:

The bonds that can rotate freely in the peptide linkage (backbone) should be given.

Concept introduction:

The single or sigma bonds are freely rotate, but double bonds are not freely rotate.

Amino acids are linked each other by peptide bonds is called protein (one or more peptide bonds). Peptide bonds are amide bonds, in which carbonyl group of one amino acid bonded to amino group of other amino acid.

The lone pair of nitrogen and pi-bond of carbonyl group undergoes delocalization, so the peptide bond has resonance.