Amine reactivity

Primary cycloaUphatic amines react with phosgene to form isocyanates. Reaction of isocyanates with primary and secondary amines forms ureas. Dehydration of ureas or dehydrosulfuri2ation of thioureas results in carhodiimides. The nucleophilicity that deterrnines rapid amine reactivity with acid chlorides and isocyanates also promotes epoxide ring opening to form hydroxyalkyl- and dihydroxyalkylaniines. Michael addition to acrylonitrile yields stable cyanoethylcycloalkylarnines. 

The amine-reactive 5-(dimethylamino)naphthalene-l-sulfonyl (dansyl) chloride 28 [80] and related fluorophores [81, 82], as well as the 5-((2 aminoethyl)amino) naphthalene-1-sulfonic acid (EDANS) 29, are included in the naphthalene fluorophore family. Derivatives of the latter, such as compound 30, exhibit a Lm.ix/ Lem 336/520 nm, molar absorptivity (e) of 6.1 x 103 M-1 cm-1, and a fluorescent quantum yield of 0.27 in water [83], The use of EDANS is particularly interesting in FRET experiments [84, 85]. Furthermore, 4-amino-3,6-disulfonylnaphthalimides (e.g., Lucifer yellow 31), associated to a longer absorption (Lmax 428 nm) [86] are suitable polar tracers [87]. 

Three types of reactive spectrally distinct fluorophores, namely lissamine rhoda-mine (LR) 80, 7-dimethylaminocoumarin (DMAC) 81, and bodipy-630 (BDPY) 82 dyes, prepared by coupling 3-azidopropylamine or propargylamine to commercially available amine-reactive dyes were evaluated for the use in selective dye-labeling of newly synthesised proteins in Rat-1 fibroblasts. 

Meng Q, Yu M, Zhang H et al (2007) Synthesis and application of /V-hydroxysuccinimidyl rhodamine B ester as an amine-reactive fluorescent probe. Dyes Pigm 73 254—260... 

A series of amine-reactive, long-wavelength fluorescent labels 48a-48c was recently developed on the basis of a norsquaraine chromophore [97, 98], Importantly, norsquaraine dyes show shifted pK3 values as compared to norcyanines with the same heterocyclic end-groups by several pH units e.g., while the unsymmetri-cal norsquaraine 48b has a p/C, around 11.2, the norcyanine dye 47d carrying the same substituents has a p/sTa of 7.5 [118]. Due to this pATa-shift to the alkaline pH range, some of these norsquaraines are also useful as fluorescent labels as their spectral properties are not affected in the pH range below 7.5. 

Alternatively, proteins can be labeled selectively using amine-reactive dyes. Particularly, cysteine and lysines can be modified covalently with a variety of commercially available fluorophores including Texas Red, Oregon Green, and Cy3 [19] (see also Chapter 6 for small molecule FRET probes, and Chapter 12 depicting a variety... 

Fella C, Walker GF, Ogris M, Wagner E (2008) Amine-reactive pyridylhydrazone-based PEG reagents for pH-reversible PEI polyplex shielding. Eur J Pharm Sci 34 309-320... 

Carbohydrate molecules containing amine groups, such as D-glucosamine, easily may be conjugated to other macromolecules using a number of amine reactive chemical reactions and crosslinkers (Chapter 2, Section 1 and Chapter 3). Some polysaccharides containing acetylated... 

Figure 3.3 EDC may be used in tandem with sulfo-NHS to create an amine-reactive protein derivative containing active ester groups. The activated protein can couple with amine-containing compounds to form amide bond linkages.

Dimethyl pimelimidate (DMP) is a homobifunctional crosslinking agent that has imidoester groups on either end (Thermo Fisher). The imidoesters are amine reactive to give stable amidine linkages with target molecules. The 7-atom bridge created by DMP crosslinks is non-cleavable and... 

Dimethyl suberimidate, DMS, is a homobifunctional crosslinking agent-containing amine-reactive imidoester groups on both ends. The compound is reactive toward the s-amine groups... 

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