Which statement regarding the tertiary structure of Ribonuclease A interactions is true?

• A. Its tertiary structure can only be stabilized by noncovalent bonds/interactions.
• B. Each of its amino acid R groups has the capability to be involved in tertiary structure stabilization.
• C. Its nonpolar amino acids do not stabilize tertiary structure.
• D. Its disulfide bridges are a type of noncovalent interaction.

Answer: (B)

Verified step by step guidance

1. Understand that the tertiary structure of a protein like Ribonuclease A (RNase A) is the three-dimensional shape formed by the folding of its polypeptide chain, which is stabilized by various interactions.
2. Recognize that the stabilization of tertiary structure involves both covalent and noncovalent interactions. Covalent interactions include disulfide bridges, while noncovalent interactions include hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals forces.
3. Disulfide bridges are covalent bonds formed between the sulfur atoms of cysteine residues, which are crucial for stabilizing the tertiary structure of proteins like RNase A.
4. Each amino acid's R group (side chain) can participate in different types of interactions that stabilize the tertiary structure. For example, polar R groups can form hydrogen bonds, charged R groups can form ionic bonds, and nonpolar R groups can participate in hydrophobic interactions.
5. Evaluate the given statements: The statement 'Each of its amino acid R groups has the capability to be involved in tertiary structure stabilization' is true because all R groups can potentially contribute to the stabilization through various interactions.