Chapter 19, Problem 19.42E

Interpretation Introduction

(a)

Interpretation:

The type of interaction present between the side chains of tyrosine and glutamine is to be stated.

Concept introduction:

The structure of proteins has four stages. These four stages are: primary, secondary, tertiary and quaternary structures. In primary structure, the amino acids are arranged to give the backbone of protein. In secondary structure, the pattern of the peptide chain is arranged in certain order. In tertiary structure, the interactions between the side chains of amino acids are considered. In quaternary structure, two or more peptide chains are linked.

Answer to Problem 19.42E

The type of interaction present between the side chains of tyrosine and glutamine is hydrogen bonding.

Explanation of Solution

The structures of tyrosine and glutamine are shown in Figure 1.

Figure 1

In tyrosine, the side chain has ${\text{CH}}_2{\text{C}}_6{\text{H}}_4\text{OH}$ group and glutamine has ${\left({\text{CH}}_2\right)}_2{\text{CONH}}_{\text{2}}$ group. The type of interaction that is possible between the side chains of the two amino acids is hydrogen bonding. This is because both nitrogen and oxygen are electronegative atoms and are linked with hydrogen atoms.

Therefore, the type of interaction present between the side chains of tyrosine and glutamine is hydrogen bonding.

Conclusion

The type of interaction present between the side chains of tyrosine and glutamine is hydrogen bonding.

Interpretation Introduction

(b)

Interpretation:

The type of interaction present between the side chains of aspartate and lysine is to be stated.

Concept introduction:

The structure of proteins has four stages. These four stages are: primary, secondary, tertiary and quaternary structures. In primary structure, the amino acids are arranged to give the backbone of protein. In secondary structure, the pattern of the peptide chain is arranged in certain order. In tertiary structure, the interactions between the side chains of amino acids are considered. In quaternary structure, two or more peptide chains are linked.

Answer to Problem 19.42E

The type of interaction present between the side chains of aspartate and lysine is salt bridge.

Explanation of Solution

The structures of aspartate and lysine are shown in Figure 2.

Figure 2

In aspartate, the side chain has ${\text{CH}}_2{\text{COO}}^{-}$ group and lysine has ${\left({\text{CH}}_{\text{2}}\right)}_{\text{4}}{\text{NH}}_{\text{3}}^{\text{+}}$ group. The type of interaction that is possible between the side chains of the two amino acids is ionic bonding which results in the formation of salt bridge. This is because the ionized side chains are present in both the amino acids. Therefore, the type of interaction present between the side chains of aspartate and lysine is salt bridge.

Conclusion

The type of interaction present between the side chains of aspartate and lysine is salt bridge.

Interpretation Introduction

(c)

Interpretation:

The type of interaction present between the side chains of leucine and isoleucine is to be stated.

Concept introduction:

The structure of proteins has four stages. These four stages are: primary, secondary, tertiary and quaternary structures. In primary structure, the amino acids are arranged to give the backbone of protein. In secondary structure, the pattern of the peptide chain is arranged in certain order. In tertiary structure, the interactions between the side chains of amino acids are considered. In quaternary structure, two or more peptide chains are linked.

Answer to Problem 19.42E

The type of interaction present between the side chains of leucine and isoleucine is hydrophobic interaction.

Explanation of Solution

The structures of leucine and isoleucine are shown in Figure 3.

Figure 3

In leucine, the side chain has ${\text{CH}}_2\text{CH}{\left({\text{CH}}_3\right)}_2$ group and isoleucine has $\text{CH}\left({\text{CH}}_3\right){\text{CH}}_2{\text{CH}}_3$ group. The type of interaction that is possible between the side chains of the two amino acids is hydrophobic. This is because the hydrophobic alkyl chains are present in both the amino acids. Therefore, the type of interaction present between the side chains of leucine and isoleucine is hydrophobic interaction.

Conclusion

The type of interaction present between the side chains of leucine and isoleucine is hydrophobic interaction.

Interpretation Introduction

(d)

Interpretation:

The type of interaction present between the side chains of phenylalanine and valine is to be stated.

Concept introduction:

The structure of proteins has four stages. These four stages are: primary, secondary, tertiary and quaternary structures. In primary structure, the amino acids are arranged to give the backbone of protein. In secondary structure, the pattern of the peptide chain is arranged in certain order. In tertiary structure, the interactions between the side chains of amino acids are considered. In quaternary structure, two or more peptide chains are linked.

Answer to Problem 19.42E

The type of interaction present between the side chains of phenylalanine and valine is hydrophobic interaction.

Explanation of Solution

The structures of phenylalanine and valine are shown in Figure 4.

Figure 4

In phenylalanine, the side chain has ${\text{CH}}_2{\text{C}}_6{\text{H}}_5$ group and valine has $\text{CH}{\left({\text{CH}}_3\right)}_2$ group. The type of interaction that is possible between the side chains of the two amino acids is hydrophobic. This is because the hydrophobic alkyl chains are present in both the amino acids. Therefore, the type of interaction present between the side chains of phenylalanine and valine is hydrophobic interaction.

Conclusion

The type of interaction present between the side chains of phenylalanine and valine is hydrophobic interaction.