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edman-degradation-is-the-principle-behind-hplcs-and-protein-identification

Related: [[./Biological Science MOC|Biological Science MOC]]

Edman degradation = amino acids in a polypeptide/protein chain are taken off one by one from the N-terminus of the chain

  • they can “break off” from the chain because the terminus end can be modified by phenylisothiocyanate (PITC). PITC modifies the free alpha-amino group to the point where it can be cleaved off via an acid.
  • the released amino acid is then characterized via its elution profile using [[./high-performance liquid chromatography (HPLC)|high-performance liquid chromatography]]
    • this is a column chromatography method!
  • after the amino acid is cleaved, the terminus returns to a normal amino group. so if you want to keep going, you need to repeat the edman degradation

Potential issues

  • alpha terminus is blocked: if the alpha terminus has been chemically modified by other chemical groups (formyl/acetyl groups), edman degradation will not work/not work well
    • potential solution: you can try to digest the protein with a protease and then sequence it. this could leave off a bit of the end of the peptide chain/some amino acids, though it might be better than nothing

![[./edman degradation is the principle behind HPLCs and protein identification2025-01_14.png|edman degradation is the principle behind HPLCs and protein identification2025-01_14.png]]