- The MALDI-TOF/TOF peptide maps were obtained from the tryptic digests of the Fc fragments excised from non-reducing and non-boiled SDS-PAGE gel. The identification of the amino acid sequences was performed as described in the legend to Table 2. The identified “common” and “discriminatory” peptides are marked with asterisks followed by the reference numbers of the respective amino acid sequences. The plus and minus symbols indicate the presence and absence of a given peptide in the maps of the individual antibodies, respectively. To distinguish the presence of a “unique” peptide, the plus symbol is framed