COLLISIONAL-ACTIVATED DECOMPOSITION OF BENZYLOXYCARBONYL-PROTECTED TRIPEPTIDE DERIVATIVES CONTAINING PROLINE IN FAST-ATOM-BOMBARDMENT MASS-SPECTROMETRY

The effect on the fragmentations of N-benzyloxycarbonyl-protected trip eptide ethyl esters due to the existence of L-proline in the gas phase was examined by the collisional-activated decomposition of the deprot onated molecule and the fragment ions produced by the cleavage of the tripeptide derivatives containing the neutral amino acids (L-alanine, L-leucine and L-phenylalanine) and L-proline, in which changes in both the numbers and positions of the prolyl residues were observed, in ne gative-ion fast atom bombardment mass spectrometry. The cleavage patte rns of these ions in the collisional-activated decomposition mass spec tra were observed to depend on the numbers and positions of prolyl res idues in the peptide derivatives. These results indicate that the conf ormational differences in the peptide derivatives due to the existence of L-proline affect the decomposition of the ions containing the neut ral amino acids in the gas phase.