Edman degradation, developed by Pehr Edman, is a method of sequencing amino acids in a peptide. In this method, the amino-terminal residue is labeled and cleaved from the peptide without disrupting other peptide bonds between other amino acid residues. phenylisothiocyanate is reacted with uncharged terminal amino group, under mildly alkaline conditions, to form a phenylthiocarbamoyl derivative. Then, under acidic conditions, this derivative of the terminal amino acid is cleaved as a thiazolinone derivative. The thiazolinone amino acid is then selectively extracted into an organic solvent and treated with acid to form the more stable phenylthiohydantoin (PTH)- amino acid derivative that can be identified by using chromatography or electrophoresis. This procedure can then be repeated again to identify the next amino acid. A major drawback to this technique is that the peptides being sequenced in this manner cannot have more than 50 to 60 residues. This is because the Edman degradation reaction is not 100% efficient, meaning that the cleavage step does not occur every time. However, this problem can be resolved by cleaving large peptides into smaller peptides before proceeding with the reaction. It is able to accurately sequence up to 30 amino acids with 98% efficiency per amino acid. An advantage of the Edman degradation is that it only uses 10 - 100 picomoles of peptide for the sequencing process. Pehr Victor Edman (April 14, 1914 —† March 19, 1977) was a swedish biochemist. ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... Peptides (from the Greek πεπτος, digestible), are the family of short molecules formed from the linking, in a defined order, of various α-amino acids. ... A residue, broadly, is anything left behind by a reaction or event. ... Diagram showing the π-bonded amino acids and the point of rotation A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (H2O). ... Isothiocyanate is the chemical group -N=C=S, formed by substituting sulfur for oxygen in the isocyanate group. ... For alternative meanings see acid (disambiguation). ... A chemist is shown using column chromatographic apparatus in the mid-1950s to separate constituents in a coal tar color analysis Pictured is a sophisticated gas chromatography system. ... Electrophoresis is the movement of an electrically charged substance under the influence of an electric field. ... In mathematics, a sequence is a list of objects (or events) arranged in a linear fashion, such that the order of the members is well defined and significant. ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... The general structure of an α-amino acid molecule, with the amine group on the left and the carboxyl group on the right. ... For other meanings of Pico see Pico (disambiguation) Pico (symbol p) is a prefix in the SI system of units denoting a factor of 10-12. ... Peptides (from the Greek πεπτος, digestible), are the family of short molecules formed from the linking, in a defined order, of various α-amino acids. ...

Mechanism for Edman Degradation