FAST-ATOM-BOMBARDMENT MASS-SPECTRA OF N-PHOSPHORYLATED PEPTIDE ANALOGS

A series of N-(N-alkyl)- and N-(O-alkyl)phosphopeptide analogs were de termined by positive and negative ion fast atom bombardment mass spect rometry and their fragmentation pathways were investigated. Their mass spectra gave abundant [MH - NH2R'](+), [MH - HOR ''](+), [MH - H2O]() or [M - H - NH2R'](-), [M - H - HOR ''](-) ions, which contained pen tavalent tricoordinate phosphorus ions through the loss of amine or wa ter. In the positive ion mass spectra, +NH3R' and +NH3CHRCONHR' were f ound, while [MH - NH2CHRCONHR'](+) was suppressed. In the negative ion mass spectra, the pseudomolecular ion [M - H](-) was the base peak, a nd almost all the fragment ions contained a phosphoryl group. (C) 1997 by John Wiley & Sons, Ltd.