Chapter 15, Problem 15.101P

(a)

Interpretation Introduction

Interpretation:

The amino acid that possesses the given $\text{R}$ group has to be named and the force that arises in the interaction of those groups has to be given.

  ${\text{-CH}}_{\text{2}}{\text{-SH with SH-CH}}_{\text{2}}\text{-}$

Concept Introduction:

Intermolecular forces:

The weaker forces that are formed between the molecules to bind together in groups are known as intermolecular forces or secondary bonds.  The intermolecular is generally defined by the term Vanderwaal forces.

Intermolecular forces in proteins:

• The back bone of the protein chain forms by covalent peptide bonds.
• The hydrogen bonds between $\text{C=O}$ of one peptide bond and $\text{N-H}$ of another peptide bond forms helical or sheet-like segments.
• Polar and ionic side chains protrude into the surrounding cell fluid interacting with water through ion-dipole forces and hydrogen bonding.
• Non-polar side chains interact through dispersion forces.
• The $\text{-SH}$ ends of two cysteine side chains forms a covalent $\text{-S-S-}$ bond, a disulfide bridge.
• Salt linkage is formed by oppositely charged ends of side chains ${\text{-COO}}^{\text{-}}$ and ${\text{-NH}}_{\text{3}}{}^{\text{+}}$.
• The hydrogen bonds between side chains keeps the distant chain portions nearer.

Explanation of Solution

The given $\text{R}$ groups are

  ${\text{-CH}}_{\text{2}}{\text{-SH with SH-CH}}_{\text{2}}\text{-}$

The $\text{R}$ groups belongs to the amino acid Cysteine.  The amino acid cysteine structure is

The forces that are involved in the interaction of $\text{R}$ groups of cysteine are disulfide bond (covalent bond).

(b)

Interpretation Introduction

Interpretation:

The amino acid that possesses the given $\text{R}$ group has to be named and the force that arises in the interaction of those groups has to be given.

  $\text{-}{\left({\text{CH}}_{\text{2}}\right)}_{\text{4}}{\text{-NH}}_{\text{3}}^{\text{+}}\text{ with }\text{O}\text{-}\stackrel{\stackrel{\text{O}}{\text{||}}}{\text{C}}{\text{-CH}}_{\text{2}}\text{-}$

Concept Introduction:

Intermolecular forces:

The weaker forces that are formed between the molecules to bind together in groups are known as intermolecular forces or secondary bonds.  The intermolecular is generally defined by the term Vanderwaal forces.

Intermolecular forces in proteins:

• The back bone of the protein chain forms by covalent peptide bonds.
• The hydrogen bonds between $\text{C=O}$ of one peptide bond and $\text{N-H}$ of another peptide bond forms helical or sheet-like segments.
• Polar and ionic side chains protrude into the surrounding cell fluid interacting with water through ion-dipole forces and hydrogen bonding.
• Non-polar side chains interact through dispersion forces.
• The $\text{-SH}$ ends of two cysteine side chains forms a covalent $\text{-S-S-}$ bond, a disulfide bridge.
• Salt linkage is formed by oppositely charged ends of side chains ${\text{-COO}}^{\text{-}}$ and ${\text{-NH}}_{\text{3}}{}^{\text{+}}$.
• The hydrogen bonds between side chains keeps the distant chain portions nearer.

Explanation of Solution

The given $\text{R}$ groups are

  $\text{-}{\left({\text{CH}}_{\text{2}}\right)}_{\text{4}}{\text{-NH}}_{\text{3}}^{\text{+}}\text{ with }\text{O}\text{-}\stackrel{\stackrel{\text{O}}{\text{||}}}{\text{C}}{\text{-CH}}_{\text{2}}\text{-}$

The $\text{R}$ group $\text{-}{\left({\text{CH}}_{\text{2}}\right)}_{\text{4}}{\text{-NH}}_{\text{3}}^{\text{+}}$ belongs to the amino acid Lysine and the $\text{R}$ group $\text{O}\text{-}\stackrel{\stackrel{\text{O}}{\text{||}}}{\text{C}}{\text{-CH}}_{\text{2}}\text{-}$ belongs to the amino acid Aspartic acid.  The amino acids Lysine and Aspartic acid structures are

The positively charged $\text{R}$ group ($\text{-}{\left({\text{CH}}_{\text{2}}\right)}_{\text{4}}{\text{-NH}}_{\text{3}}^{\text{+}}$) of Lysine is attracted by the negatively charged $\text{R}$ group ($\text{O}\text{-}\stackrel{\stackrel{\text{O}}{\text{||}}}{\text{C}}{\text{-CH}}_{\text{2}}\text{-}$) of Aspartic acid.  It forms the salt linkage.

(c)

Interpretation Introduction

Interpretation:

The amino acid that possesses the given $\text{R}$ group has to be named and the force that arises in the interaction of that groups has to be given.

  ${\text{ -CH}}_{\text{2}}\text{-}\stackrel{\stackrel{\text{O}}{\text{||}}}{\text{C}}{\text{-NH}}_{\text{2}}{\text{- with HO-CH}}_{\text{2}}\text{-}$

Concept Introduction:

Intermolecular forces:

The weaker forces that are formed between the molecules to bind together in groups are known as intermolecular forces or secondary bonds.  The intermolecular is generally defined by the term Vanderwaal forces.

Intermolecular forces in proteins:

• The back bone of the protein chain forms by covalent peptide bonds.
• The hydrogen bonds between $\text{C=O}$ of one peptide bond and $\text{N-H}$ of another peptide bond forms helical or sheet-like segments.
• Polar and ionic side chains protrude into the surrounding cell fluid interacting with water through ion-dipole forces and hydrogen bonding.
• Non-polar side chains interact through dispersion forces.
• The $\text{-SH}$ ends of two cysteine side chains forms a covalent $\text{-S-S-}$ bond, a disulfide bridge.
• Salt linkage is formed by oppositely charged ends of side chains ${\text{-COO}}^{\text{-}}$ and ${\text{-NH}}_{\text{3}}{}^{\text{+}}$.
• The hydrogen bonds between side chains keeps the distant chain portions nearer.

Explanation of Solution

The given $\text{R}$ groups are

  ${\text{ -CH}}_{\text{2}}\text{-}\stackrel{\stackrel{\text{O}}{\text{||}}}{\text{C}}{\text{-NH}}_{\text{2}}{\text{ with HO-CH}}_{\text{2}}\text{-}$

The $\text{R}$ group ${\text{ -CH}}_{\text{2}}\text{-}\stackrel{\stackrel{\text{O}}{\text{||}}}{\text{C}}{\text{-NH}}_{\text{2}}$ belongs to the amino acid Asparagine and the $\text{R}$ group ${\text{ HO-CH}}_{\text{2}}\text{-}$ belongs to the amino acid Serine.  The amino acids Asparagine and Serine structures are

The $\text{R}$ groups ${\text{-NH}}_{\text{2}}\text{ and -OH}$ forms the hydrogen bonding.

(d)

Interpretation Introduction

Interpretation:

The amino acid that possesses the given $\text{R}$ group has to be named and the force that arises in the interaction of that groups has to be given.

Concept Introduction:

Intermolecular forces:

The weaker forces that are formed between the molecules to bind together in groups are known as intermolecular forces or secondary bonds.  The intermolecular is generally defined by the term Vanderwaal forces.

Intermolecular forces in proteins:

• The back bone of the protein chain forms by covalent peptide bonds.
• The hydrogen bonds between $\text{C=O}$ of one peptide bond and $\text{N-H}$ of another peptide bond forms helical or sheet-like segments.
• Polar and ionic side chains protrude into the surrounding cell fluid interacting with water through ion-dipole forces and hydrogen bonding.
• Non-polar side chains interact through dispersion forces.
• The $\text{-SH}$ ends of two cysteine side chains forms a covalent $\text{-S-S-}$ bond, a disulfide bridge.
• Salt linkage is formed by oppositely charged ends of side chains ${\text{-COO}}^{\text{-}}$ and ${\text{-NH}}_{\text{3}}{}^{\text{+}}$.
• The hydrogen bonds between side chains keeps the distant chain portions nearer.

Explanation of Solution

The given $\text{R}$ groups are

The $\text{R}$ group $\text{-}\stackrel{\stackrel{{\text{CH}}_3}{\text{|}}}{\text{C}}{\text{-CH}}_3$ belongs to the amino acid Valine and the $\text{R}$ group ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{-CH}}_{\text{2}}\text{-}$ belongs to the amino acid Phenylalanine.  The amino acids Valine and Phenylalanine structures are

The $\text{R}$ groups $\text{-}\stackrel{\stackrel{{\text{CH}}_3}{\text{|}}}{\text{C}}{\text{-CH}}_3$ and ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{-CH}}_{\text{2}}\text{-}$ are non-polar and the interaction occurs by dispersion forces.