Proteins Edman degradation

Edman degradation (Section 27 13) Method for determining the N terminal amino acid of a peptide or protein It in volves treating the material with phenyl isothiocyanate (CgH5N=C=S) cleaving with acid and then identifying the phenylthiohydantoin (PTH derivative) produced Elastomer (Section 10 11) A synthetic polymer that possesses elasticity... 

The general idea of peptide sequencing by Edman degradation is to cleave one amino acid at a time from an end of the peptide chain. That terminal amino acid is then separated and identified, and the cleavage reactions are repeated on the chain-shortened peptide until the entire peptide sequence is known. Automated protein sequencers are available that allow as many as 50 repetitive sequencing cycles to be carried out before a buildup of unwanted by products interferes with the results. So efficient are these instruments that sequence information can be obtained from as little as 1 to 5 picomoles of sample—less than 0.1 /xg. 

Amino acid sequencing may be carried out in a number of ways. The most widely used is the Edman degradation procedure in which phenylisothiocyanate is used to react with the amino acid residue at the amine end of the protein chain. This derivatized residue is removed from the remainder of the protein and converted to a phenylhydantoin derivative which is identified by using, for example, HPLC. 

Edman degradation A method of amino acid sequencing in proteins in which successive V-terminal amino acids are removed from the polypeptide chain and identified. 

The ability to visualize spots on a 2D gel, while useful as a fingerprint, is not the same as protein identification. Protein sequencing by the Edman degradation technique is the classical means of determining... 

N-terminal sequencing is normally undertaken by Edman degradation (Figure 7.5). Although this technique was developed in the 1950s, advances in analytical methodologies now facilitate fast and automated determination of up to the first 100 amino acids from the N-terminus of most proteins, and usually requires a sample size of less than 1 umol to do so (Figure 7.6). 

Fietzek, P. P., and Kiihn, K. Automation of the Sequence Analysis by Edman Degradation of Proteins and Peptides. 29, 1-28 (1972). 

A number of ribosomal proteins contain modihed amino acids at the N terminus or at other positions of the protein chain (Table IV). The N termini of three proteins (S5, S18, and L7) are acetylated, thus they cannot be subjected successfully to manual or automatic Edman degradation because of their blocked N termini. Mutants have been isolated in... 

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