Edman Degradation
Edman Degradation — A method of sequencing peptides by chemically removing one amino acid at a time from the N-terminus and identifying it chromatographically.
What Is Edman Degradation?
Edman degradation is a classical method for determining peptide amino acid sequences by sequentially removing and identifying one residue at a time from the N-terminus. Developed by Pehr Edman in 1950, it remained the primary sequencing method for 40 years before being largely replaced by tandem mass spectrometry.
The Edman Cycle
- Coupling: Phenyl isothiocyanate (PITC) reacts with the free N-terminal amino group
- Cleavage: Anhydrous acid cleaves the derivatized N-terminal residue as a thiazolinone
- Identification: Convert to stable PTH-amino acid and identify by HPLC
- Repeat: The shortened peptide is ready for the next cycle
Current Use
Limited to ~50 residues per run due to cumulative yield losses. Cannot sequence through proline efficiently. Blocked N-termini (pyroglutamate, acetylation) prevent reaction. Now used mainly when MS/MS data is ambiguous or for confirming N-terminal identity of recombinant products.
Frequently Asked Questions
What is Edman Degradation?
A method of sequencing peptides by chemically removing one amino acid at a time from the N-terminus and identifying it chromatographically.
Why is Edman Degradation important in peptide research?
Edman Degradation is a fundamental concept in analytical as it relates to peptide science. It directly influences experimental design, compound characterization, and the reliability of research outcomes across biochemistry and molecular biology disciplines.
Authority Sources
- Edman Degradation on Wikipedia
- Search Edman Degradation on PubChem (NIH)
- Research articles on ScienceDirect