Chapter 23, Problem 8TE

To determine

The building blocks of a protein molecule.

Answer to Problem 8TE

The building blocks of protein are the $\text{α-}$ amino acids.

Explanation of Solution

The carboxylic acids having an amino group are termed as amino acids. The general structure of amino acid has an amino $\left(-{\text{NH}}_2\right)$ group, carboxylic $\left(-\text{COOH}\right)$ group and a hydrogen atom attached to carbon atom along with a side chain.

The interaction of $-{\text{NH}}_2$ group of one amino acid with $-\text{COOH}$ group of another amino acid leads to the formation of an amide linkage. A number of amino acid units are joined with each other through $-\text{CONH}-$ linkages and results in the formation of peptides. This linkage is named as peptide linkage.

The relative position of the $-{\text{NH}}_2$ group with respect to $-\text{COOH}$ group, the classification of amino acid is made as $\text{α-}$, $\text{β-}$, $\text{γ-}$, and $\text{δ-}$. The hydrolysis product of only $\text{α-}$ amino acids is protein. Thus, the $\text{α-}$ amino acids are considered as the building blocks of proteins.

Conclusion:

Protein is the polymer of peptide which is composed of $>100$ $\text{α-}$ amino acid units. Therefore, the $\text{α-}$ amino acids are considered as the building blocks of proteins.