Collisional‐activated decomposition of benzyloxycarbonyl‐protected tripeptide derivatives containing proline in fast atom bombardment mass spectrometry

Abstract

The effect on the fragmentations of N-benzyloxycarbonyl-protected tripeptide ethyl esters due to the existence of L-proline in the gas phase was examined by the collisional-activated decomposition of the deprotonated 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 negative-ion fast atom bombardment mass spectrometry. The cleavage patterns of these ions in the collisional-activated decomposition mass spectra were observed to depend on the numbers and positions of prolyl residues in the peptide derivatives. These results indicate that the conformational differences in the peptide derivatives due to the existence of L-proline affect the decomposition of the ions containing the neutral amino acids in the gas phase. <ii.y [ I ) I . J r V X~S I~~I < T