Proteolytic fragmentation of channel catfish antibodies

Specifically purified anti-DNP antibodies from channel catfish were digested with pepsin or trypsin under various conditions and the resultant fragments analyzed in terms of their physico- and immunochemical properties. The results indicated that pepsinolysis of channel catfish antibodies to small peptides was exceedingly rapid and failed to yield stable recognizable fragments under any conditions used. However, trypsinolysis was considerably more successful. In particular, tryptic digestion at 37 degrees C gave good yields of ligand binding material that undoubtedly represented Fab fragments. In addition, it was observed that limited trypsinolysis at 4 degrees C yielded somewhat larger Fab-like material, tentatively designated as Fab' fragments. Hence, it would appear that in spite of their previously reported peculiar covalent tetrameric structure, channel catfish antibodies do exhibit an intramolecular architecture or organization similar to that seen in more conventional polymeric antibodies from other species.