A protein treated with FDNB shows two DNP peaks in HPLC analysis. What does this indicate about the protein?

• A. The protein has two identical subunits.
• B. The protein has two subunits, each with a distinct N-terminal residue.
• C. The protein is a monomer with two N-terminal residues.
• D. The protein has no N-terminal residues.

Answer: (B)