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Click Chemistry Building Blocks

The reaction scheme of a biomolecule alkyne with a dye azide.
"Click Chemistry" is a term introduced by K. B. Sharpless in 2001 to describe reactions that are high in yields, wide in scope, and create only by-products that can be removed without chromatography. Click chemistry reactions are stereospecific, simple to perform and can be conducted in easily removable or benign solvents. This concept was developed in parallel with the interest within the pharmaceutical, material, and other industries in capabilities of generating large libraries of compounds for screening in discovery research. Several types of reaction have been identified that fulfill these criteria. They are thermodynamically-favored reactions that lead specifically to one product, such as nucleophilic ring opening reactions of epoxides and aziridines; non-aldol type carbonyl reactions, such as formation of hydrazones and heterocycles; eletrophilic additions to carbon-carbon multiple bonds, such as oxidative formation of epoxides and Michael Additions; and cycloaddition reactions.

The reaction scheme of a biomolecule azide with a dye alkyne.
An examination of the azide-alkyne cycloaddition shows that it fulfills many of the prerequisites. The copper-catalyzed azide"alkyne cyloaddition is a two-step process. First, one reaction partner-either an azide or alkyne linked to a "building block" such as a peptide or an oligonucleotide, is incorporated by conventional synthesis. Subsequently, the other reaction partner-the complementary alkyne or azide linked to a fluorescent dye, biotin or other detection reagent-is "clicked" into place in the presence of catalytic copper (I). One reaction partner must be an azide derivative and the other an alkyne derivative, but functional moiety can serve as either the incorporated molecule or the detection molecule. The reaction is also regiospecific, yielding exclusively 1,4-disubstituted-1,2,3-triazole linkages. The 1,2,3-triazole linkage between a peptide or an oligonucleotide and a dye is extremely stable. It is not susceptible to hydrolysis, oxidation or reduction. AAT Bioquest offers a variety of dye azides and alkynes for labeling peptides and oligonucleotides. These clickable reagents include both common fluorescent dyes (e.g., fluoresceins, rhodamines and cyanines) and non-fluorescent quenchers. Our Tide Fluor™ and Tide Quencher™ dyes are specifically optimized for preparing novel FRET substrates.

Table 1. Dye Azides for Labeling Oligonucleotides and Peptides

Cat No.
Product Name
Ex (nm)
Em (nm)
EC (cm-1M-1)
Unit Size
508AMCA Azide35345518,0000.183 0.1531 mg$106
143Cyanine 3 azide [equivalent to Cy3® azide]555565150,0000.0420.0731 mg$106
153Cyanine 5 azide [equivalent to Cy5® azide]649665250,0000.0260.0301 mg$106
178Cyanine 5.5 azide [equivalent to Cy5.5® azide]678701230,0000.0940.1011 mg$272
163Cyanine 7 azide [equivalent to Cy7® azide]749776275,0000.0250.0361 mg$272
1315-FAM Azide49452175,0000.2470.17810 mg$162
1336-FAM Azide49451875,0000.2550.17210 mg$162
2406-HEX azide53355074,0000.3000.1275 mg$162
2486-JOE azide52054873,0000.3260.2175 mg$162
4946-ROX azide57560295,0000.3070.1795 mg$162

Table 2. Dye Alkynes for Labeling Oligonucleotides and Peptides

Cat No.
Product Name
Ex (nm)
Em (nm)
Unit Size
507AMCA Alkyne3534551 mg$106
144Cyanine 3 alkyne [equivalent to Cy3® alkyne]5555651 mg$106
154Cyanine 5 alkyne [equivalent to Cy5® alkyne]6496651 mg$106
179Cyanine 5.5 alkyne [equivalent to Cy5.5® alkyne]6787011 mg$272
164Cyanine 7 alkyne [equivalent to Cy7® alkyne]7497761 mg$272
1325-FAM Alkyne49451810 mg$162
1346-FAM Alkyne49451810 mg$162
2416-HEX alkyne5335505 mg$162
2496-JOE alkyne5205485 mg$162
4956-ROX alkyne5756025 mg$162