- The MALDI-TOF/TOF peptide maps were obtained from the tryptic digests of the Fab fragments excised from the non-reducing and non-boiled SDS-PAGE gel. The peptides were identified from the MS and MS/MS spectra using the Mascot search engine against the Swiss-Prot and NCBInr sequence databases. The identified peptide is marked with an asterisk symbol. By definition, the “common” peptides were present in the maps of all of the analyzed antibody clones, as indicated by plus symbols