--- title: "Edman degradation Template – Chemistry Diagram | MolDraw" url: https://www.moldraw.com/templates/edman-degradation/ description: "Edman degradation template: The N-terminal amine adds to phenyl isothiocyanate to give the PTC-peptide; in anhydrous TFA the thiocarbonyl S attacks the first…" lang: en publisher: Scidart Academy generated: 2026-11-13 --- [MolDraw](https://www.moldraw.com/) › [Templates](https://www.moldraw.com/templates/) › [Biochemistry](https://www.moldraw.com/templates/biochemistry/) › Edman degradation [Biochemistry](https://www.moldraw.com/templates/biochemistry/)Premium # Edman degradation template ![Edman degradation template: The N-terminal amine adds to phenyl isothiocyanate to give the PTC-peptide; in anhydrous TFA the thiocarbonyl S attacks the first peptide C=O and the shortened peptide leaves as an amine, giving the anilinothiazolinone (ATZ), which aqueous acid converts to the PTH-amino acid.](https://www.moldraw.com/templates/edman-degradation.webp) [Edit in MolDraw](https://www.moldraw.com/)Download with Pro Premium template. Preview and edit it free in MolDraw; downloading and exporting it is part of [MolDraw Pro](https://www.moldraw.com/pricing). The N-terminal amine adds to phenyl isothiocyanate to give the PTC-peptide; in anhydrous TFA the thiocarbonyl S attacks the first peptide C=O and the shortened peptide leaves as an amine, giving the anilinothiazolinone (ATZ), which aqueous acid converts to the PTH-amino acid. ## Mechanism step by step PITC tags the N-terminal residue; anhydrous acid cuts it off as a thiazolinone and leaves the rest of the chain intact 1. **Coupling (pH 9)** – The free α-NH₂ adds to the N=C=S carbon 2. **Proton transfer** – The phenylthiocarbamoyl (PTC) peptide 3. **Protonation (TFA)** – Anhydrous acid protonates the first peptide C=O 4. **Cyclisation** – Sulfur bonds to the activated carbonyl carbon (5-membered ring); the anilino N takes the positive charge 5. **Proton transfer** – H⁺ moves from O to the next residue’s N (via the solvent) 6. **Peptide leaves** – C=O reforms and the shortened peptide departs as a neutral amine 7. **Deprotonation** – The anilinothiazolinone (ATZ), extracted into organic solvent 8. **Conversion** – Aqueous acid opens the ATZ and recloses it to the stable PTH-amino acid ## Key points - Coupling needs the free, unprotonated α-NH₂ (pH 8–9); the cleavage is done in anhydrous acid so that no other peptide bond is hydrolysed. - Only the first residue is removed. The shortened peptide goes round the cycle again, one residue per cycle, read by HPLC of the PTH-amino acids. - Repetitive yields of about 99% limit a run to roughly 30–50 residues; longer proteins are cut into fragments first, and a blocked N-terminus stops it. - Unlike Sanger’s FDNB method, Edman degradation does not destroy the rest of the chain. Edman and Begg automated it in the sequenator (1967). Drawn with 312 atoms, 25 arrows, 12 shapes – every one editable in MolDraw. ## Sources - [Nelson & Cox, Lehninger Principles of Biochemistry, 8th ed., 2021, ch. 3](https://openlibrary.org/isbn/9781319228002) Textbook - [Berg, Tymoczko, Gatto & Stryer, Biochemistry, 9th ed., 2019](https://openlibrary.org/isbn/9781319114657) Textbook - [Edman, Arch. Biochem. 1949, 22, 475](https://pubmed.ncbi.nlm.nih.gov/18134557/) Original paper - [Edman & Begg, Eur. J. Biochem. 1967, 1, 80](https://pubmed.ncbi.nlm.nih.gov/6059350/) Original paper ## How to use this template 1. Press **Edit in MolDraw**. The template opens on the canvas of the free MolDraw editor. 2. Change anything: move structures, edit atoms and labels, recolour highlights or delete what you do not need. 3. Add your own structures, arrows and text next to it, or combine several templates on one page. 4. Export the drawing as PNG, SVG or PDF for slides, worksheets, theses and papers. ## Frequently asked questions ### Is the Edman degradation template free? You can preview the Edman degradation template here and open and edit it in MolDraw for free. Downloading or exporting it is part of MolDraw Pro, together with the other premium templates. ### Can I edit the Edman degradation template? Yes. It opens as an ordinary MolDraw drawing, so every structure, arrow, label and colour can be changed, and you can add your own content around it. ### Is the chemistry checked? Every structure is checked with RDKit and every curly arrow passes MolDraw’s electron-flow audit. The sources used are listed on this page. ### Are the biochemical pathways drawn with structures? Yes. 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