Elementary plant Biochemistry and Biotechnology (2+1)

C-terminal identification

• C-terminal amino acid can be determined by methods similar to those used for the N-terminal acid.
• Hydrazine is used to find out the C-terminal amino acid.
• It reacts with the carbonyl group of each peptide bond except C-terminal amino acid.
• The bond is cleaved and each amino acid derivative is released as the hydrazide derivative (hydrazinolysis).
• Since the carboxyl group of C-terminal amino acid is not involved in a peptide. bond, it remains in the mixture as the only unmodified amino acid.
• After chromatographic separation and comparison with the standards, the C-terminal amino acid can be identified.
  
• Carboxypeptidases are used for enzymic determination of the C-terminal amio acid.