91Ó°ÊÓ

In the primary structure of a protein, the bond formed between carboxyl carbon of one amino acid and amino group of another amino acid is called the peptide bond. Peptide bonds form the backbone of the protein or the polypeptide.

Hence,peptide bond is between Nitrogen (N) of amino group and Carbon (C) of carboxyl group.

The Nitrogen of amino group is represented by the blue colored balls, and the Carbons of carboxyl group are represented by the gray colored balls in Fig. 6-7.

Hence, to count the number of peptide bonds present in the right handed α helix provided in Fig. 6-7, we have to count the number of bonds between the blue colored balls (N of amino group) and the gray colored balls (C of carboxyl group).

As we can see from Fig. 6-7, there are 10 bonds between the blue colored balls (N of amino group) and the gray colored balls (C of carboxyl group). Therefore, 10 polypeptide bonds are shown in the structure in Fig. 6-7.