Which statement is true about disulfide bonds and protein folding?

• A. Disulfide bonds are formed between the amino and carboxyl groups of amino acids.
• B. Disulfide bonds are covalent bonds that stabilize the tertiary structure of proteins.
• C. Disulfide bonds are primarily involved in the primary structure of proteins.
• D. Disulfide bonds are non-covalent interactions that occur in the quaternary structure of proteins.

Answer: (B)

Verified step by step guidance

1. Understand the role of disulfide bonds in protein structure. Disulfide bonds are covalent bonds formed between the sulfur atoms of two cysteine amino acids, which help stabilize the protein's tertiary structure.
2. Recognize that disulfide bonds are not involved in the primary structure of proteins. The primary structure is the sequence of amino acids linked by peptide bonds, not disulfide bonds.
3. Clarify that disulfide bonds are not non-covalent interactions. They are covalent, meaning they involve the sharing of electrons between atoms, specifically between sulfur atoms in cysteine residues.
4. Identify that disulfide bonds are not formed between amino and carboxyl groups. They specifically form between the thiol groups of cysteine residues.
5. Conclude that disulfide bonds play a crucial role in stabilizing the tertiary structure of proteins, contributing to the overall 3D shape and functionality of the protein.