Phenyl isothiocyanate acid determination

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... 

Albin, D. M., Wubben, J. E., and Gabert, V. M., Effect of hydrolysis time on the determination of amino acids in samples of soybean products with ion-exchange chromatography or precolumn derivatization with phenyl isothiocyanate,. Agr. Food Chem., 48, 1684, 2000. 

A more useful procedure, in that it allows sequential determination of the A-terminal amino acids in a peptide, is the Edman degradation. This process removes the A-terminal amino acid, but leaves the rest of the chain intact, so allowing further reactions to be applied. The reagent used here is phenyl isothiocyanate. 

V Fierabracci, P Masiello, M Novelli, E Bergamini. Application of amino acid analysis by high-performance liquid chromatography with phenyl isothiocyanate derivatization to the rapid determination of free amino acids in biological samples. J Chromatogr 570 285-291, 1991. 

The N-terminal amino acid of a protein can be determined by reacting the protein with dansyl chloride or fluorodinitrobenzene prior to acid hydrolysis. The amino acid sequence of a protein can be determined by Edman degradation which sequentially removes one residue at a time from the N terminus. This uses phenyl isothiocyanate to label the N-terminal amino acid prior to its release from the protein as a cyclic phenylthiohydantoin amino acid. 

A molecular weight determination has shown that an unknown peptide is a pentapeptide, and an amino acid analysis shows that it contains the following residues one Gly, two Ala, one Met, one Phe. Treatment of the original pentapeptide with carboxypeptidase gives alanine as the first free amino acid released. Sequential treatment of the pentapeptide with phenyl isothiocyanate followed by mild hydrolysis gives the following derivatives ... 

The amino acid composition of peptides is generally assayed by carrying out acid hydrolysis with 6 M hydrochloric acid, followed by determination of the individual amino acids by HPLC. Various types of HPLC have been employed to separate amino acids, but reversed-phase chromatography on Cigcoiumns is the most commonly system used. Detection of amino acids normally involves derivatization, since their maximum absorbance is at 214 nm in which many other compounds also can absorb. The most frequently used derivatizing agents are dansyl chloride, phenyl isothiocyanate and o-phthaldialdehyde. 

Determining the structure of a peptide or protein is carried out in several steps. The identity and amount of each amino acid present in a peptide is determined by amino acid analysis. The peptide is hydrolyzed to its constituent a-amino acids, which are then separated and identified. Next, the peptide is sequenced. Edman degradation by treatment with phenyl isothiocyanate (PITC) cleaves one residue from the N terminus of the peptide and forma an easily identifiable phenylthvobydantoin (PTH) derivative of the N-terminal amino acid. A series of sequential Edman degradations allows the sequencing of a peptide chain up to 50 residues in length. 

An instrument which operates on the phenyl isothiocyanate degradation scheme has been developed for the automatic determination of amino acid sequences in proteins and peptides.4... 

Of the various chemical methods developed for determining the amino acid sequence of a polypeptide, the one most widely used today is the Edman degradation, introduced in 1950 by Pehr Edman of the University of Lund, Sweden. In this procedure, a polypeptide is treated with phenyl isothiocyanate, C6H5N = C=S, and then with acid. The effect of Edman degradation is to remove the A terminal amino acid selectively as a substituted phenylthiohydantoin (Eigure 18.8), which is then separated and identified. 

The Edman degradation uses phenyl isothiocyanate to remove and identify the N-terminal amino acid of peptides or proteins. The Edman degradation can be repeated and automated so that the sequence of up to 20 to 30 N-terminal amino acids can be determined. 

Edman s reagent phenyl isothiocyanate. A reagent used to determine the N-terminal amino acid of a polypeptide. 

Alternative Reagents. 1-(1-Phenyl)ethyl isocyanate (PEI) is a cheaper alternative to NEI however, diastereomers formed from NEI are usually easier to separate by liquid chromatography. Other alternatives are also used, e.g. in determining the enantiomeric purity of 3-aminoquinuclidine, PEI, NEI, 2,3,4,6-tetraacetyl-p-D-glucopyranosyl isothiocyanate, and (R,R)- and (S,S)-0,0-dibenzoyltartaric acid anhydride are all employed successfully. Mandelic Acid and Mosher s reagent, a-methoxytrifluoromethylphenylacetyl chloride, may not be quite as effective as NEI when resolutions are carried out by liquid chromatography. ... 

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