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Review
. 2016 Oct 24;21(10):1393.
doi: 10.3390/molecules21101393.

Development and Applications of the Copper-Catalyzed Azide-Alkyne Cycloaddition (CuAAC) as a Bioorthogonal Reaction

Li Li  1   2 , Zhiyuan Zhang  3
Affiliations
Review

Development and Applications of the Copper-Catalyzed Azide-Alkyne Cycloaddition (CuAAC) as a Bioorthogonal Reaction

Li Li et al. Molecules. .

Abstract

The emergence of bioorthogonal reactions has greatly broadened the scope of biomolecule labeling and detecting. Of all the bioorthogonal reactions that have been developed, the copper-catalyzed azide-alkyne cycloaddition (CuAAC) is the most widely applied one, mainly because of its relatively fast kinetics and high efficiency. However, the introduction of copper species to in vivo systems raises the issue of potential toxicity. In order to reduce the copper-induced toxicity and further improve the reaction kinetics and efficiency, different strategies have been adopted, including the development of diverse copper chelating ligands to assist the catalytic cycle and the development of chelating azides as reagents. Up to now, the optimization of CuAAC has facilitated its applications in labeling and identifying either specific biomolecule species or on the omics level. Herein, we mainly discuss the efforts in the development of CuAAC to better fit the bioorthogonal reaction criteria and its bioorthogonal applications both in vivo and in vitro.

Keywords: CuAAC; activity-based protein profiling; bioorthogonal reactions; click reaction; imaging.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Bioorthogonal strategy for biomolecule labeling.
Scheme 1
Scheme 1
Examples of bioorthogonal reactions. (a) ketone/aldehyde condensation; (b) Staudinger reaction; (c) 1,3 bipolar cycloaddition; (d) Inverse-electron demand Diels-Alder reaction.
Scheme 1
Scheme 1
Examples of bioorthogonal reactions. (a) ketone/aldehyde condensation; (b) Staudinger reaction; (c) 1,3 bipolar cycloaddition; (d) Inverse-electron demand Diels-Alder reaction.
Scheme 2
Scheme 2
CuAAC reaction and the proposed mechanism. (a) CuAAC reaction; (b) Early mechanism proposal by Sharpless; (c) Mechanism proposal with a dinuclear copper intermediate.
Scheme 3
Scheme 3
Accelerating ligands for CuAAC reactions: (a) TBTA and its analogues; (b) tris(heteroarylmethyl)amine ligands; (c) 2,2′-bipyridine and 1,10-phenanthroline derivatives; (d) tris(1-benzyl-1H-1,2,3-triazol-4-yl)methanol; (e) L-histidine; (f) P-donor ligands.
Figure 2
Figure 2
Bioorthogonal labeling of biomolecules with CuAAC.
Figure 3
Figure 3
Traditional ABPP (a) vs. CuAAC-assisted ABPP (b).
Scheme 4
Scheme 4
Chelating azides for CuAAC reactions: (a) chelation-assisted CuAAC; (b) 2-picolylazide; (c) A19 and A20; (d) AIO-1.
Scheme 5
Scheme 5
Cyclooctyne derivatives for the SPAAC reaction.
See this image and copyright information in PMC

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