Dansyl amide

Glycerol ethoxyquin, dansyl amides 20-fold spray solution, 33% in methanol [292] or 50% ethanol [245]... 

Tnethanolaimne dansyl amino acids, enhancement dansyl amides... 

Triton X-100 dansyl amides and amino acids 30 to 110-fold spray solution, 20% in chloroform [265, 290]... 

Draw a picture in your notebook of the polyamide thin-layer plate exposed under UV light after each of the two or three solvent developments. These pictures should look similar to Figure E2.7. Three fluorescent areas should be evident after solvent 2 however, better separation is achieved by solvent 3. A blue fluorescent area at the bottom of the plate is dansic acid (DNS-OH), which is a hydrolysis product of dansyl chloride. A blue-green fluorescent spot about one-third to one-half up the plate is dansyl amide (DNS-NH2), which is produced by reaction of dansyl chloride with ammonia. A third spot, which usually fluoresces green, is the dansyl derivative of the NH2-terminus amino acid. Note the positions of the standard dansyl amino acids and compare with the unknown. What is the identity of the NH2-terminal amino acid Are any other fluorescent spots evident on the plate Using polarity or nonpolarity, try to explain the position of each molecule on the thin-layer plate. 

Dansyl chloride and phenylisothiocyanate (PITC) are the derivatizating agents most used in UV detection. Dansyl chloride reacts with the primary and secondary amino groups of peptides in a basic medium (pH 9.5), forming dansylated derivatives that are very stable to hydrolysis but are photosensitive. The derivatives are detectable in UV at 254 nm and by fluorescence. Dansyl sulfonic acid is formed as a by-product of the reaction, and excess reagent reacts with the dansyl derivatives to form dansyl amide the conditions of derivatization must therefore be optimized in order to avoid the formation of such by-products to the extent possible. The conditions of the reaction with dansyl chloride and of the separation of the derivatives thus formed have been thoroughly studied (83,84). Martin et al. (85) carried out derivatization using an excess concentration of dansyl chloride of 5 -10-fold in a basic medium (lithium carbonate, pH 9.5) in darkness for 1 h. 

The observation that Zn(II) incorporation into apocarbonic anhydrase in the presence of dansylamide raises the fluorescence of the dansyl-amide (69) has led to the adoption of the dansyl group as a pendant accessory to cyclen to generate a Zn(II)-sensitive fluorophore 54 (70-72). 

To prove this concept, a set of nanombes were prepared with the green fluorescent silane 7/-(triethoxysilylpropyl)dansyl-amide attached to their inner surfaces, and the hydrophobic octadecyl silane (Cig) to their outer surfaces. These nanombes were added to a vial containing water and the immiscible organic solvent cyclohexane, which were mixed and allowed to separate. Because these nanombes are hydrophobic on their outer surfaces, they partition into the (upper) cyclohexane phase (Figure 24.3B). This may be in contrast to nanombes that were labeled on their inner surfaces with the blue fluorescent silane triethoxysUyl-propylquinineurethan, but were not labeled with any silane on their outer surfaces. When the same experiment is done on these... 

Triethanolamine dansyl ammo acids, dansyl amides enhancement spray solution, 20% in 2-propanol, fluonmetnc evaluation after 16 h storage m vacuo [281]... 

For analytical purposes, amines espedaUy biogenic amines, are frequently derivatized using N-dimethylnaphthalenesulfonylchloride to form the so-called dansyl amides. These derivatives generate the N-dimethylaminonaphthalene ion at m/z 171 upon electron impact ionization, especially ih the case of low energy electrons . Thus, the transition m/z (171 + SOj -f- amine — 1) 171 was applied... 

Dansylethyl chloroformate is used in the same way as FMOC-Q it reacts rapidly with hydroxyl groups if the pH of the reaction medium is around 9 The fluorescence characteristics of the derivatives of dansyl-elhyl chloroformate are similar to those of the dansyl-amides, and therefore the reagent should be preferable to FMOC-Cl and NCF-Cl. 

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