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 alkyne is reactive with azide 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, Jäschke 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

5.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

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

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