C-terminal sequencing method for peptides and proteins by the reaction with a vapor of perfluoric acid in acetic anhydride

A successive C-terminal amino acid truncation reaction of peptides and proteins with a vapor generated from a low-concentrated perfluoric acid in acetic anhydride is presented. The reaction products were analyzed with matrix-assisted laser desorption/ionization-time of flight mass-spectrometry giving molecular mass ions of the C-terminal truncated peptides or proteins from which the C-terminal sequence information can be deduced. Acetylation reaction preceded the truncation reaction in order to protect the amino groups and other reactive groups in peptides and proteins, and after the truncation reaction, hydration reaction was carried out to afford cleaner mass spectra.