Structural Characterization of Cyclic Peptides using a Quadrupole Time-of-Flight Mass Spectrometer

Cyclic peptides are expected to be a new class of therapeutic agents because of their higher stability in vivo and higher cell permeability than linear peptides. MS/MS-based peptide sequencing is the most common effective strategy for structural identification of linear peptides. However, in the case of cyclic peptides, sufficient sequence information cannot be obtained with MS/MS measurement as the fragmentation patterns are quite complicated due to the cyclic nature. In order to overcome this issue, we have attempted to confirm the structural characteristics of cyclic peptides only by spectral assignment.