Click chemistry describes a class of chemical reactions that use bio-orthogonal or biologically unique moieties to label and detect a molecule of interest in mild, aqueous conditions. The click reaction involves a copper-catalyzed triazole formation from an azide and an alkyne. The azide and alkyne moieties can be used interchangeably; either one can be used to tag the molecule of interest, while the other is used for subsequent detection.

The 5-FAM azide  is reactive with terminal alkyne via a copper-catalyzed click reaction that allows the subsequent visualization by fluorescence spectroscopy.

Efficiency—the click reaction is complete in less than 1 hour;

Specificity—the reaction between the label and detection tag is selective and specific;

Stability—the reaction product contains an irreversible, covalent bond;

Biologically inert—the components of the reaction do not undergo any side reactions.

1.Click-mediated labeling of bacterial membranes through metabolic modification of the lipopolysaccharide inner core.

Dumont A, Malleron A, Awwad M, Dukan S, Vauzeilles B,Angew Chem Int Ed Engl (2012) 51:3143-3146

2.Site-specific terminal and internal labeling of RNA by poly(A) polymerase tailing and copper-catalyzed or copper-free strain-promoted click chemistry.

Winz ML, Samanta A, Benzinger D, J?schke A,Nucleic Acids Res (2012) 40:e78-e78

3.Mutant methionyl-tRNA synthetase from bacteria enables site-selective N-terminal labeling of proteins expressed in mammalian cells.

Ngo JT, Schuman EM, Tirrell DA,Proc Natl Acad Sci U S A (2013) 110:4992-4997

4.Alkynyl sugar analogs for the labeling and visualization of glycoconjugates in cells.

Hsu TL, Hanson SR, Kishikawa K, Wang SK, Sawa M, Wong CH Proc Natl Acad Sci U S A (2007) 104:2614-2619

5.Metabolic labeling of sialic acids in living animals with alkynyl sugars.

Chang PV, Chen X, Smyrniotis C, Xenakis A, Hu T, Bertozzi CR, Wu P Angew Chem Int Ed Engl (2009) 48:4030-4033