title: N-Terminal dual protein functionalization by strain-promoted alkyne-nitrone cycloaddition.
abstract: Strain-promoted alkyne-nitrone cycloadditon (SPANC) was optimized as a versatile strategy for dual functionalization of peptides and proteins. The usefulness of the dual labeling protocol is first exemplified by the simultaneous introduction of a chloroquine and a stearyl moiety, two endosomal escape-improving functional groups, into the cell-penetrating peptide hLF (human lactoferrin). Additionally, we demonstrate that dual labeling of proteins is feasible by combining metal-free and copper-catalyzed click chemistry. First, SPANC is applied to enhanced green fluorescent protein to introduce both biotin and a terminal alkyne. The terminal acetylene then serves as a convenient anchor point for the CuAAC reaction with azido-containing fluorescein, thereby demonstrating the potential of combined SPANC and CuAAC for the straightforward, dual functionalization of proteins.
authors.affiliation: Synthetic Organic Chemistry, Institute for Molecules and Materials, Radboud University Nijmegen, Nijmegen, The Netherlands.
authors.forename: Rinske P
authors.initials: RP
authors.lastname: Temming
authors.forename: Loek
authors.initials: L
authors.lastname: Eggermont
authors.forename: Mark B
authors.initials: MB
authors.lastname: van Eldijk
authors.forename: Jan C M
authors.initials: JC
authors.lastname: van Hest
authors.forename: Floris L
authors.initials: FL
authors.lastname: van Delft
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D001710:Biotin / Q000737:chemistry*; D057930:Click Chemistry; D003500:Cyclization; D049452:Green Fluorescent Proteins / Q000737:chemistry*; D006801:Humans; D007781:Lactoferrin / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009589:Nitrogen Oxides / Q000737:chemistry*
chemical_list: D000480:Alkynes; D009589:Nitrogen Oxides; C485184:enhanced green fluorescent protein; C015388:nitrones; D049452:Green Fluorescent Proteins; D001710:Biotin; D007781:Lactoferrin