In situ N‐phosphorylation of oligopeptides for fast atom bombardment mass spectrometry

Abstract

Positive ion fast atom bombardment mass spectrometry (FABMS) of in situ N‐phosphorylated oligopeptides showed intense quasi‐molecular ions together with the successive alkene loss fragment ions, which afford multiple checks of the unequivocal reality of the relative molecular mass of the tested samples. More interesting, in a novel cleavage pattern only the N‐phosphoryl fragment ions gave intense peaks, the C‐terminal series ions being suppressed. For each of the N‐terminal ions, losses of alkenes also occur to provide multiple checks for the existence of these ions. The FABMS of the in situ N‐ phosphorylated oligopeptides might provide an easily accessible routine method for peptide sequencing.