Elementary plant Biochemistry and Biotechnology (2+1)

N-terminal identification

• Fluoro dinitro benzene (FDNB), known as Sanger's reagent, was used to identify the N-terminal amino acid.
  
• This reagent was replaced by dansyl chloride and Edman's reagent (phenyl isothiocyanate, PITC).
• Edman's reagent is also used to determine the amino acid sequence of a polypeptide chain from the N-terminal by subjecting the polypeptide to repeated cycles of Edman degradation.
• After every cycle, the newly liberated phenylthiohydantoin (PTH) amino acid was identified.
• The sequence of peptides containing 30-40 amino acids can be determined using a sequencer by adopting the Edman's degradation method