Chapter 23, Problem 48A

Interpretation Introduction

Interpretation:

The number of peptide bonds present in peptide having five amino acids should be calculated.

Concept introduction:

Proteins are polymeric biomolecules which are formed by the polymerisation of amino acids. Amino acids are the organic molecules with $–{\text{NH}}_{\text{2}}$ and −COOH functional groups bonded on same carbon atom of the molecule.

They polymerise by peptide linkage to form dipeptide, oligopeptide and polypeptide molecules. Each peptide bond formation is a condensation reaction that occurs with the elimination of water molecule.

Answer to Problem 48A

Four peptide bonds (amide groups −CONH₂) are present in a peptide having five amino acids.

Explanation of Solution

A chemical bond which is formed between two molecules of amino acid, when carboxyl group of one amino acid reacts with amino group of another amino acid and water is released is known as amide bond.

The structure of peptide bond:

The structure having five amino acids is:

In above structure, five different amino acids are present due to the presence of four peptide bonds. Peptide bonds are identified by the bonding present between carboxyl group of one amino acid and amino group of another amino acid. Four amide groups are present in the given structure and the amino acids present on end of the chain (both side) is not bonded to any group.

Thus, four peptide bonds (amide groups −CONH₂) are present in a peptide having five amino acids.