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 Cy3 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

4.Direct in-gel fluorescence detection and cellular imaging of O-GlcNAc-modified proteins.

Clark PM, Dweck JF, Mason DE, Hart CR, Buck SB, Peters EC, Agnew BJ, Hsieh-Wilson LC,J Am Chem Soc (2008) 130:11576-11577

5.Robust fluorescent detection of protein fatty-acylation with chemical reporters.

Charron G, Zhang MM, Yount JS, Wilson J, Raghavan AS, Shamir E, Hang HC,J Am Chem Soc (2009) 131:4967-4975