title: Copper-assisted click reactions for activity-based proteomics: fine-tuned ligands and refined conditions extend the scope of application.
abstract: Copper-catalysed alkyne-azide 1,3-dipolar cycloaddition (CuAAC) is the predominantly used bioconjugation method in the field of activity-based protein profiling (ABPP). Several limitations, however, including conversion efficiency, protein denaturation and buffer compatibility, restrict the scope of established procedures. We introduce an ABPP customised click methodology based on refined CuAAC conditions together with new accelerating copper ligands. A screen of several triazole compounds revealed the cationic quaternary {3-[4-({bis[(1-tert-butyl-1H-1,2,3-triazol-4-yl)methyl]amino}methyl)-1H-1,2,3-triazol-1-yl]propyl}trimethylammonium trifluoroacetate (TABTA) to be a superior ligand. TABTA exhibited excellent in vitro conjugation kinetics and optimal ABPP labelling activity while almost exclusively preserving the native protein fold. The application of this CuAAC-promoting system is amenable to existing protocols with minimal perturbations and is even compatible with previously unusable buffer systems such as Tris⋅HCl.
authors.affiliation: Fakultät für Chemie, Lehrstuhl für Organische Chemie II, Technische Universität München, Lichtenbergstraße 4, 85748 Garching (Germany).
authors.forename: Georg C
authors.initials: GC
authors.lastname: Rudolf
authors.forename: Stephan A
authors.initials: SA
authors.lastname: Sieber
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D001386:Azides / Q000737:chemistry*; D057930:Click Chemistry / Q000379:methods*; D003300:Copper / Q000737:chemistry*; D061565:Cycloaddition Reaction; D008024:Ligands; D040901:Proteomics / Q000379:methods*; D014230:Triazoles / Q000737:chemistry; D014269:Trifluoroacetic Acid / Q000737:chemistry
chemical_list: D000480:Alkynes; D001386:Azides; D008024:Ligands; D014230:Triazoles; D003300:Copper; D014269:Trifluoroacetic Acid
keywords: ABPP; CuAAC; analytical methods; click chemistry; proteomics