On study of computer-assisted carboxypeptidase method for C-terminal sequence determination of proteins or peptides, two computer programs, DPS and CPA, were successfully developed on VAX-11/780 computer and tested with some synthetic peptides and degradation fragments of natural protein as model substrates. The C-terminal sequence of CB-3, one of the CNBr degradation fragments of trichosanthin was determine by this method as: -SerAlaSerAlaAlaLeuHseOH, which was later confirmed by other ways of sequencing. This method is not only able to extend the C-terminal sequencing up to 7 amino acid residues, but also useful for determing the C-terminal sequence with some amino acids residues appearing in repetition.

Key words: POLYPEPTIDE, RADIX TRICHOSANTHIS, AMINO ACID SEQUENCE ANALYSIS, CARBOXYL PEPTIDASE, COMPUTER AIDED DESIGN, PROTEIN, PROGRAMMING SYSTEMS