Chapter 23, Problem 49A

Interpretation Introduction

(a)

Interpretation:

The approximate molecular weight of insulin (51 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.

Number of amino acids is calculated as:

$\text{Number of amino acids}=\frac{\text{Molecular mass of an amino acid}}{\text{Total molecular mass}}$

Answer to Problem 49A

Approximate molecular weight of insulin = $5610\text{ g/mole}$

Explanation of Solution

The average molecular mass of an amino acid = 110 g/mole

Insulin consists of 51 amino acids.

The mathematical expression is:

$\text{Number of amino acids}=\frac{\text{Molecular mass of an amino acid}}{\text{Total molecular mass}}$

Put the values,

$\text{51}=\frac{\text{Molecular mass of insulin}}{\text{110 g/mole}}$

Molecular mass of insulin = $51\times 110\text{ g/mole}$

= $5610\text{ g/mole}$

Interpretation Introduction

(b)

Interpretation:

The approximate molecular weight of myosin (1750 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.

Number of amino acids is calculated as:

$\text{Number of amino acids}=\frac{\text{Molecular mass of an amino acid}}{\text{Total molecular mass}}$

Answer to Problem 49A

Approximate molecular weight of myosin = $192,500\text{ g/mole}$

Explanation of Solution

The average molecular mass of an amino acid = 110 g/mole

Myosin consists of 1750 amino acids.

The mathematical expression is:

$\text{Number of amino acids}=\frac{\text{Molecular mass of an amino acid}}{\text{Total molecular mass}}$

Put the values,

$\text{1750}=\frac{\text{Molecular mass of myosin}}{\text{110 g/mole}}$

Molecular mass of myosin = $1750\times 110\text{ g/mole}$

= $192,500\text{ g/mole}$