Amino acids dabsyl chloride

FIGURE 4.20 Determination of the amino-terminal residue of a peptide. Dabsyl chloride labels the peptide, which is then hydrolyzed with the use of hydrochloric acid. The dabsyl-amino acid (dabsyl-alanine in this example) is identified by its chromatographic characteristics. 

Derivatization with dabsyl chloride (94) was applied for the separation of primary amino acids in physiological samples, prior to determination of their specific radioactivity. The derivatization is easy to perform and the derivatives are stable252. 

Various procedures are used to analyze protein primary structure. Several protocols are available to label and identify the amino-terminal amino acid residue (Fig. 3-25a). Sanger developed the reagent l-fluoro-2,4-dinitrobenzene (FDNB) for this purpose other reagents used to label the amino-terminal residue, dansyl chloride and dabsyl chloride, yield derivatives that are more easily detectable than the dinitrophenyl derivatives. After the amino-terminal residue is labeled with one of these reagents, the polypeptide is hydrolyzed to its constituent amino acids and the labeled amino acid is identified. Because the hydrolysis stage destroys the polypeptide, this procedure cannot be used to sequence a polypeptide beyond its amino-terminal residue. However, it can help determine the number of chemically distinct polypeptides in a protein, provided each has a different amino-terminal residue. For example, two residues—Phe and Gly—would be labeled if insulin (Fig. 3-24) were subjected to this procedure. 

Dabsyl Chloride (4-dimethyl-aminoazobenzene-4-sulfonyl chloride) Aabs = 420 nm. Derivatives are very stable (days) and can be formed from both primary and secondary amino acids. Detection is by absorption only. Detection limits are in the high picomole range. Reaction time is typically around 10 minutes at 70°C. Completeness of reaction can be adversely affected by the presence of high levels of various salts. Because reaction efficiency is highly matrix dependent and variable for different amino acids, standard amino acid solution should be derivatized under similar conditions/matrix for accurate calibration. Commercial systems available uti-... 

EHJM Jansen, RH van den Berg, R Both-Miedema, L Doom. Advantages and limitations of precolumn derivatization of amino acids with dabsyl chloride. J Chromatogr 553 123-133, 1991. 

Dabsyl chloride is an alternative to DABITC as a derivatization reagent to be used for manual sequencing. Dabsyl chloride reacts with primary and secondary amino acids forming red-orange derivatives that are stable for months. The method offers excellent sensitivity, ease, and speed of preparation and high-resolution capabilities. However, it suffers from interferences with ammonia present in biological samples. Furthermore, it results in a relatively reduced column lifetime due to the utilization of excess of Dabsyl chloride [9]. 

A peptide composed of 12 amino acids does not react with dabsyl chloride or with phenyl iso thiocyanate. Cleavage with cyanogen bromide yields a peptide "with a carboxyl-terminal homoserine lactone residue, which is readily hydrolyzed, in turn yielding a peptide whose sequence is determined by the Edman procedure to be... 

Dabsyl chloride (DBS-Cl) (4,4-dimethylaminoazobenzene-4-sulphonyl-chloride). The reaction of amino acids with dabsyl chloride produces a compound which can be detected at the picomole level using UV detection (436 nm). The product is stable at room temperature (Lin, 1984) but has not received the same attention as other reagents (Chang et al., 1984). 

Peptide analysis, sequencing and synthesis All fluorescent dye labels with reactive groups for amine, dansyl chloride, dabsyl chloride. Fluorescent isothiocyanates. N-Terminal amino acid analysis, peptide sequencing, peptide synthesis, labeling peptides in solution, solid-phase synthesis of labeled peptides 37... 

Chloride [56512-49-3]. 4 -Dimethylaminoazobenzene-4-sulfonyl chloride. Dabsyl chloride C,4H,4C1N302S M 323.802 Fluorogenic reagent for amines, amino acids and alcohols. Deep red cryst. Mp 186-188°. 

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