Question

Identify the protein with more than one polypeptide chain.

• A. Myoglobin
• B. Trypsin
• C. Immunoglobulin
• D. Lysozyme

Answer 1

The correct option is C Immunoglobulin

Myoglobin is a small oxygen-binding protein of muscle cells with a single polypeptide chain of 153 amino acid residues and a single iron protoporphyrin, or heme, group. Trypsin is a globular protein with 24kD and one polypeptide chain of 220 residues and serves as a proteolytic enzyme. Lysozyme is abundant in egg white and human tears and catalyzes the hydrolytic cleavage of polysaccharides in the protective cell walls of some families of bacteria. It has a single peptide chain of 129 amino acid residues arranged mostly in $\alpha$ helical segments. Immunoglobulin has four polypeptide chains: two large ones are called as heavy chains and two light chains which are linked by non-covalent and disulfide bonds. The heavy chains interact at one end, then branches to interact separately with the light chains thereby forming a Y-shaped molecule. The correct answer is C.