Edman

Edman is a surname. The name is most notably associated with Pehr Edman, a Swedish biochemist who devised the Edman degradation, a method for sequencing amino acids from the N-terminus of peptides and proteins.

Edman degradation, or Edman sequencing, is a stepwise chemical procedure in which the N-terminal amino acid is selectively labeled with phenylisothiocyanate (the Edman reagent) and converted into a phenylthiohydantoin (PTH) derivative after treatment with acid. This PTH-amino acid is identified by chromatographic methods, and the remaining peptide is left with a new N-terminus for the next cycle. Repetition yields the amino-terminal sequence.

Typically, the method can reliably determine sequences up to about 30-50 residues under favorable conditions. It requires a free, unmodified N-terminus and is less effective for peptides with blocked or modified termini, or for highly hydrophobic or long peptides. Modern protein sequencing relies mainly on mass spectrometry, but Edman degradation remains useful for sequencing short peptides or confirming N-terminal residues.

History: The technique was introduced in the 1950s by Pehr Edman and became widely used in protein chemistry before the advent of mass spectrometry–based methods.