Question

The number of disulphide linkages present in insulin are

• A. $1$
• B. $2$
• C. $3$
• D. $4$

Answer 1

The correct option is C $3$

Insulin contains $51$ amino acids arranged in two polypeptide chains containing $21$ and $30$ amino acid residues respectively. These two chains are joined together by two disulphide cross links. In addition, the smaller polypeptide chain ($21$ amino acids) has also an internal disulphide linkage. Hence, option (c) is correct.