Copper‐Free Postsynthetic Labeling of Nucleic Acids by Means of Bioorthogonal Reactions

Abstract

Postsynthetic modification of nucleic acids has the advantage that the chemical development of only a few building blocks is necessary, each bearing a chosen reactive functional group that is applicable to its reactive counterpart for a variety of different labeling types. The reactive group is either linked to phosphoramidites for chemical synthesis on solid phase or attached to nucleoside triphosphates for application in primer extension experiments and PCR. Chemoselectivity is required for this strategy, together with bioorthogonality to perform these labelings in living cells or even organisms. Currently, the copper-free reactions include strain-promoted 1,3-dipolar cycloadditions, "photoclick" reactions, Diels-Alder reactions with inverse electron demand, and nucleophilic additions. The majority of these modification strategies show good to excellent reaction kinetics, an important prerequisite for labeling inside cells and in vivo in order to keep the concentrations of the reacting partners as low as possible.

Chemistry Can Make Strict and Fuzzy Controls for Bio-Systems: DNA Nanoarchitectonics and Cell-Macromolecular Nanoarchitectonics

“…Other Cu(I)-free click-type couplings such as thiol-ene reactions, photo-click reactions, and Diels-Alder reactions have also been reported. 125 In typical laboratory protocols, alkyne-bearing oligonucleotides are labelled with the azides in dyes and other functional groups, after the products of automated DNA synthesizers are appropriately purified. Alternatively, the columns for the synthesizers can be directly subjected to on-column click reactions.…”

1H‐1,2,3‐Triazole: From Structure to Function and Catalysis

“…Utilizing the previously described and developed methods for click bioconjugation reactions, click chemistry was recently shown to be a very appealing method for the direct labeling of live cells , in which the orthogonality of the click reaction provided a means for the specific targeting of various parts of live cells, such as proteins , nucleic acids , or cell membranes . Very often these approaches utilize the SPAAC reaction, as shown by Bertozzi and co‐workers, who performed live‐cell labeling of specific protein glycoforms, providing a useful platform for investigating the roles of protein‐specific glycosylation in various cellular contexts .…”

An Unconventional Acid‐Labile Nucleobase Protection Concept for Guanosine Phosphoramidites in RNA Solid‐Phase Synthesis

“…Continuously optimized over the last decades, RNAs of up to 50 to 70 nucleotides are readily accessible. [10][11][12] The nucleoside building blocks require suitable protection of nucleobase amino and ribose 2′-hydroxy groups. Whereas the former are usually acyl protected, silyl protection (tBDMS or TOM) [13,14] of the latter are most widely applied, and orthoesters (ACE), [15] 2-cyanoethoxymethyl (CEM), [16] or thiocarbamates (TC) [17] also represent powerful alternatives.…”