What type of bonds hold together the polypeptide chains in an antibody?

What type of bonds hold together the polypeptide chains in an antibody?

• A. Ionic bonds
• B. Hydrogen bonds
• C. Peptide bonds
• D. Disulfide bonds

Answer: (D)

Disulfide bonds play a crucial role in the structure of antibodies, which are proteins composed of polypeptide chains. These covalent bonds form between the sulfur atoms of cysteine residues within the polypeptide chains, creating a strong linkage that helps stabilize the three-dimensional shape of the antibody. This structural integrity is essential for the proper functioning of antibodies, allowing them to effectively bind to antigens and perform their immune functions.

While peptide bonds also contribute to maintaining the primary structure of the polypeptide chains by linking amino acids together, they are not the specific bonds that hold the multiple polypeptide chains of an antibody together. Ionic and hydrogen bonds do contribute to interactions within and between protein molecules, but they are not as pivotal in stabilizing the overall structure of antibodies as disulfide bonds are. Thus, the role of disulfide bonds in maintaining the quaternary structure of antibodies is fundamental for their biological activity.