Chapter 23, Problem 44A

Interpretation Introduction

Interpretation:

Whether dipeptide lysine-valine is the same compound as the dipeptide valine-lysine should be determined.

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.

Explanation of Solution

Dipeptide Lysine-Valine:

The above dipeptide is formed by the reaction between lysine and valine.

The structure of Lysine is:

The structure of Valine is:

The reaction is written as:

Dipeptide Valine-Lysine:

The reaction is written as:

According to the above reactions, one can say that the dipeptide Lysine-Valine and dipeptide Valine-Lysine are not same compounds. The structures of both compounds are different as each amino acid has a different group linked to the peptide bond.