Expanded Utility of the Native Chemical Ligation Reaction

Abstract

The post-genomic era heralds a multitude of challenges for chemists and biologists alike, with the study of protein functions at the heart of much research. The elucidation of protein structure, localization, stability, post-translational modifications, and protein interactions will steadily unveil the role of each protein and its associated biological function in the cell. The push to develop new technologies has necessitated the integration of various disciplines in science. Consequently, the role of chemistry has never been so profound in the study of biological processes. By combining the strengths of recombinant DNA technology, protein splicing, organic chemistry, and the chemoselective chemistry of native chemical ligation, various strategies have been successfully developed and applied to chemoselectively label proteins, both in vitro and in live cells, with biotin, fluorescent, and other small molecule probes. The site-specific incorporation of molecular entities with unique chemical functionalities in proteins has many potential applications in chemical and biological studies of proteins. In this article, we highlight recent progress of these strategies in several areas related to proteomics and chemical biology, namely, in vitro and in vivo protein biotinylation, protein microarray technologies for large-scale protein analysis, and live-cell bioimaging.

Click Chemistry: 1,2,3‐Triazoles as Pharmacophores

“…[36,37] Reviews also describe applications in synthesis of peptidomimetics, [38,39] in bioconjugations [40][41][42] and surface chemistry. [43] It has been compared to the Staudinger ligation [37] and used in profiling of proteases [44] and in combinatorial drug discovery.…”

Diels–Alder Ligation of Peptides and Proteins

“…[17] Nevertheless, despite some notable successes, [18][19] such methods have not found widespread use (yet) after the development of the more simple and versatile chemical ligation methods. [1,[20][21][22][23][24] The size of proteins which can be chemically synthesized has been increased Because the mutually reactive groups (or at least one of them) are functionalities not normally found in peptides, the price to be paid for applying such chemoselective ligation is the formation of an unnatural structure at the ligation site. However, in practice, these unnatural structures are often well tolerated within the context of a folded protein and numerous examples of fully active proteins were prepared using these methods.…”

Dechalcogenative Allylic Selenosulfide and Disulfide Rearrangements: Complementary Methods for the Formation of Allylic Sulfides in the Absence of Electrophiles. Scope, Limitations, and Application to the Functionalization of Unprotected Peptides in Aqueous Media.

“…1,2,17 Native chemical ligation (NCL) for the synthesis of peptides and proteins, and its enzyme-promoted biochemical equivalent, expressed protein ligation, [18][19][20][21] is one such reaction that takes advantage of the sulfhydryl group and which uses it to great advantage in the highly chemoselective formation of amide bonds in aqueous solution. 10,[21][22][23][24][25][26][27][28][29][30][31] Another thiol-based method, the selective formation of mixed disulfides, is both one of the oldest and most enduring of ligation methods. 1,2,[32][33][34][35][36][37][38] The mildness of the disulfide ligation and its established chemoselectivity for the cysteine thiol in the presence of all the proteinogenic amino acids stands in stark contrast to the various other methods for cysteine functionalization, most of which involve the capture of the cysteine thiol by electrophilic species, and which consequently have obvious potential chemoselectivity issues.…”