Photoclick chemistry: a fluorogenic light-triggered in vivo ligation reaction

Abstract

The ability to use chemical reactivity to monitor and control biomolecular processes with a spatial and temporal precision motivated the development of light-triggered in vivo chemistries. To this end, the photoinduced tetrazole-alkene cycloaddition, also termed “photoclick chemistry” offers a very rapid chemical ligation platform for the manipulation of biomolecules and matrices in vivo. Here we outline the recent developments in the optimization of this chemistry, ranging from the search for substrates that offer two-photon photoactivatability, superior reaction kinetics, and/or genetic encodability, to the study of the reaction mechanism. The applications of the photoclick chemistry in protein labeling in vitro and in vivo as well as in preparing “smart” hydrogels for 3D cell culture are highlighted.

Rapid Bioorthogonal Chemistry Turn-on through Enzymatic or Long Wavelength Photocatalytic Activation of Tetrazine Ligation

“…Such ‘photoclick’ reactions generally utilize short-wavelength light to unleash more reactive species. 10,11 The direct use of red or near IR light to induce bioorthogonal reactivity has not been described. Lin has recently described two-photon based photoinducible tetrazole reactions that utilize near IR light, 8 and Popik has shown that cyclopropenones can be photodecarbonylated by a two photon process.…”

Photo‐induced and Rapid Labeling of Tetrazine‐Bearing Proteins via Cyclopropenone‐Caged Bicyclononynes

“…[10] Likewise,t etrazinebearing amino acids have been incorporated into proteins in E. coli using engineered variants of the Methanocaldococcus jannaschii (Mj)T yrosyl-tRNAs ynthetase (TyrRS)/tRNA CUA pair, and tetrazine-modified proteins have been labeled with strained TCO fluorophores in ultra-rapid iEDDAC (second order rate constants up to 10 5 m À1 s À1 ). [12] Key advances include light-triggered tetrazole-alkene photoclick chemistry, [13] visible-light induced [4+ +2] cycloaddition between 9,10-phenanthrenequinone and vinyl ethers [14] as well as photo-induced activation of cyclopropenone-caged cyclooctynes for strain-promoted azide-alkyne cycloadditions (photo-SPAAC). [12] Key advances include light-triggered tetrazole-alkene photoclick chemistry, [13] visible-light induced [4+ +2] cycloaddition between 9,10-phenanthrenequinone and vinyl ethers [14] as well as photo-induced activation of cyclopropenone-caged cyclooctynes for strain-promoted azide-alkyne cycloadditions (photo-SPAAC).…”

A Method to Generate and Analyze Modified Myristoylated Proteins

“…However, low sensitivity of autoradiographic detection of [ 3 H], toxicity associated with [ 125 I] and challenges in synthesizing radiolabelled lipids limit the applications of this method. The introduction of “click” chemistry [6] and the advancement of mass spectrometry prompted the development of azide- and alkyne-modified myristic acids and palmitic acids for identification of myristoylated [7] or palmitoylated [8] proteins, respectively. In this approach, the modified lipids were metabolically transferred to a fraction of proteins in cells, and the modified proteins are then tagged with biotin or a fluorophore through copper-catalyzed [3+2] Huisgen cycloaddition for proteomics studies, or the Staudinger ligation for live cell imaging because of the toxicity of copper [9] .…”