Anilinothiazolinone, Edman degradation

ATZ Derivative (Section 26.6) An anilinothiazolinone, formed from an amino acid during Edman degradation of a peptide. 

To sequence an entire polypeptide, a chemical method devised by Pehr Edman is usually employed. The Edman degradation procedure labels and removes only the amino-terminal residue from a peptide, leaving all other peptide bonds intact (Fig. 3-25b). The peptide is reacted with phenylisothiocyanate under mildly alkaline conditions, which converts the amino-terminal amino acid to a phenylthiocarbamoyl (PTC) adduct. The peptide bond next to the PTC adduct is then cleaved in a step carried out in anhydrous trifluo-roacetic acid, with removal of the amino-terminal amino acid as an anilinothiazolinone derivative. The deriva-tized amino acid is extracted with organic solvents, converted to the more stable phenylthiohydantoin derivative by treatment with aqueous acid, and then identified. The use of sequential reactions carried out under first basic and then acidic conditions provides control over... 

Edman degradation involves treatment of a peptide with phenyl isothiocyanate (PITC), CeHs—N=C=S, followed by treatment with trifluoroacetic acid, as shown in Figure 19.4. The first step attaches the PITC to the -NH2 group of the N-terminal amino acid, and the second step splits the N-terminal residue from the peptide chain, yielding an anilinothiazolinone (ATZ) derivative plus the chain-shortened peptide. Further acid-catalyzed rearrangement of... 

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