Before Edman degradation, Fredrick Sanger developed the first method to analyze the N-terminal amino acid of a protein using 2,4-dinitrofluorobenzene in the following reaction. Propose a mechanism for this reaction.

2,4-dinitrofluorobenzene

A chemical compound featuring a benzene ring substituted with two nitro groups (NO2) at the 2 and 4 positions and a fluorine atom at the 1 position.

N-terminal

Refers to the start of a protein or polypeptide terminated by an amino acid with a free amine group.

Amino Acid

A building block of proteins, characterized by an amino group (-NH2), a carboxyl group (-COOH), and a specific side chain.