Fluorescent Tools for Click Chemistry
effective bio-orthogonal labeling with Chromeo™ Dyes
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- Chromeo™ 488 Azide and Alkyne
- Chromeo™ 494 Azide and Alkyne
- Chromeo™ 546 Azide and Alkyne
- Chromeo™ 642 Azide and Alkyne
Click chemistry constitutes a novel approach for easy, effective labeling and detection of biomolecules in vitro and in vivo. It is based on the use of biologically unique tags as reaction partners. An azide and an alkyne undergo the copper(I)-catalyzed formation of a triazole, which forms a stable covalent bond. This reaction is based on the azide alkyne Huisgen cycloaddition, which was described by Rolf Huisgen in the 1970s. The addition of the Cu(I) catalyst changes the reaction conditions to room temperature and allows the presence of water. Figure 1 shows the reaction scheme of the click-reaction.
Figure 1: The principle of the click reaction between an azide (R1) and alkyne (R2).
Using azide or alkyne tags for labeling proteins, nucleic acids, lipids or sugars has the advantage that neither moiety occurs in nature, and neither reacts with other molecules in cellular systems. Because of its high selectivity, bio-orthogonal click-chemistry can be used for detection in complex biological samples: one of the reaction partners is integrated into the molecule of interest, while the second tag containing a fluorescent label is covalently attached by performing the click-reaction. As the reaction is highly specific and proceeds rapidly towards completion, click chemistry can also be used to synthesize large substances.
Chromeo™ Dyes – Chromeo 488, Chromeo 494, Chromeo 546 and Chromeo 642 – exhibit superior fluorescent properties, broad Stokes shifts, stability towards photobleaching and pH, and low cell toxicity. In addition, they are compatible with most excitation sources including diode lasers, LEDs, tungsten lamps and xenon arc lamps. For bio-orthogonal labeling, Chromeo Dyes are offered as click-reactive azide or alkyne.
Figure 2: Click labeling with Chromeo Dye azides.
Chromeo™ Azide and Alkyne advantages
- High fluorescent intensity
- Photostability – enables multiple exposures and increased exposure time
- pH insensitive
- Low background
- Ready to use in click-reactions
In addition to click chemistry reagents, Chromeo Dyes are offered in a variety of formats like amine reactive NHS-Esters, which have been shown to label amines in peptides, proteins or amino modified DNA. They are available conjugated to biotin or streptavidin, they are part of our easy-to-use Fluorescent Antibody Labeling Kits, and are offered as optimized Fluorescent Secondary Antibody Conjugates for enhanced detection.
Figure 3: Chromeo 546 staining in HeLa cells.