Acetylation of peptides with deuterium labelled acetic anhydride for the fast atom bombardment mass spectrometry

The specific and simplified acetylation method for the α-amino group of a peptide with deuterium labelled anhydride mixture was studied, using some model peptides. The method devised for the N-terminus analysis of a peptide by fast atom bomberdment (FAB) mass spectrometry. The Nterminal α-amino groups of peptides, Tyr-Gly-Gly-Phe-Leu and Ala-Lys-Asn-Phe-Phe, could be acetylated specifically at the range between pH 4.0 and pH 7.0. Below pH 3.0,no acetylation of the peptides were observed. The ionic species of the buffer solutions were also effective on the yields of acetylation of the peptides. The acetylation products were analyzed by HPLC and further by FAB mass spectrometry. With combination of these acetylation technique, it was possible to distinguish between the N-terminal fragment ions and the C-terminal fragment ions on FAB mass spectra