Characterization of antibodies using N-terminally truncated peptides produced in an automatic protein sequencer.

Antibodies raised against short peptides coupled via their C-terminus will often be specific for the N-terminus. Peptides lacking one or two N-terminal residues seemed useful for characterization of such antibodies. A simple method for N-terminal truncation of nmol amounts of peptides is described. An automatic protein sequencer was used as a suitable reactor. The method is generally versatile, but some structural features of the peptides limited the yields. Thus, purification and careful identification of the products was needed. The specificities of several antibodies were characterized by incubation with the singly and doubly truncated versions of the peptides used for immunization and/or standards. The results disclosed dependency on the N-terminal residue(s) varying from none to more than 10(4) times reduced binding.