Why is iodoacetate used in conjunction with beta mercaptoethanol during protein sequencing?

• A. To enhance the cleavage of peptide bonds.
• B. To label the N-terminal amino acids.
• C. To cleave peptide bonds at the C-terminal end.
• D. To prevent the reformation of disulfide bonds by carboxymethylating sulfhydryl groups.

Answer: (D)