DABITC

Other tests for the detection of amino functionalities on solid supports include the TNBS (2,4,6-trinitrobenzenesulfonic acid, picrylsulfonic acid) [Hancock and Battersby Anal Biochem 71 260 ]976], the DABITC [Shah et al. Anal. Commun. 34 325 7997] and the NF31 [Madder et al. Eur J Org Chem 2787 7999] tests. 

A couplingreagent 1.4 mg DABITC (4-(dimethylamino)azoben-zene-4 -isothiocyanate, Mr 282.4, recrystallized from acetone) is dissolved in 1.0 ml acetone. The solution is divided into 40 pi aliquots, and acetone is evaporated by nitrogen. The aliquots are stable in a desiccator at room temperature for months. 

B 2. The new reagent 4-W,W-dimethylaminoazobenzene-4 -isothiocyanate (DABITC) is often used for the Edman method of protein sequence analysis. Write a reaction showing this use of the reagent. 

Phenyl isothiocyanate is also used for peptide sequencing in combination with colored Edman s reagent 4-W-,/V -dimethy]aminoazobenzene-4 -isothiocyanate (DABITC). Prieto (48) used this DABITC-PITC procedure to determine the partial terminal N-NH2 sequence of the low-molecular-weight peptide fraction from bread dough and bread. 

Amino acids derivatized with isothiocyanates (PITC, NITC, DNITC, DABITC), with AQC. or with sulphonyl chlorides (DNS-Cl. DABS-CI)... 

Recently, 4-(dimethylamino)azobenzene-4 -isoth-iocyanate (DABITC) derivatives of amino adds have been also investigated. 

These derivatives are obtained in basic medium by the reaction of DABITC with the primary amino group of N-terminal amino adds in peptides. The color difference between DABITC (or its degradation products) and DABTH-amino adds fadlitates identification on TLC. These derivatives are colored compounds and, because of their stability and sensitivity, are usually used for qualitative and quantitative analyses of amino compounds such as amino acids and amines. 

Dimethylamino azobenzene isothiocyanate microsequencing results in red-orange derivatives, which exhibit their absorbance maximum at 420 nm with s = 47.000, in other words offering threefold higher sensitivity compared to PTH derivatives. DABITC deriva-... 

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]. 

CAPS, 3-[cyclohexylamino]-l-propanesulfonic acid DABITC, dimethylaminoazobenzene isothiocyanate DABTH, dimethylaminoazobenzene thiohydantoin OPA, o-phthalaldehyde PTC, phenylthiocarbamyl PTH, phenylthiohydantoin PVDF, polyvinylidine difluoride TFA, trifluoroacetic acid... 

Of several newer methods for visualizing proteins, DABITC (dlmethylaminoazobenzene Isothlocyanate) derivatized proteins have been used to evoke discernible bands on SDS-polyacrylamide gels... 

The identification of N-terminal amino acids in peptides and proteins is of considerable practical importance because it constitutes an essential step in the process of sequential analysis of peptide structures. Many N-amino acid derivatives have been proposed for this purpose and the ones most commonly studied by TLC are 2,4-dinitrophenyl (DNP)-and 5-dimethylaminonaphthalene-l-sulfonyl (dansyl, Dns)-amino acids, and 3-phenyl-2-thiohydantoins (PTH-amino acids). Recently, 4-(dimethylamino)azobenzaie-4/-isothio-cyanate (DABITC) and phenyl-isothiocyanate (PITC) have also been investigated as derivatizing agents of amino acids. 

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