Site-Specific Anchoring a Luminescent Tag in a Protein with Non-Emissive Iridium(III) Complex

Chembiochem. 2024 Feb 16;25(4):e202300798. doi: 10.1002/cbic.202300798. Epub 2024 Jan 16.

Abstract

Site-specific modification of proteins with synthetic fluorescent tag effectively improves the resolution of imaging, and such a labeling method with negligible three-dimensional structural perturbations and minimal impact on the biological functions of proteins is of high interest to dissect the high-resolution activities of biomolecules in complex systems. To this end, several non-emissive iridium(III) complexes [Ir(C-N)2 (H2 O)2 ]+ OTF- (C-N denotes various cyclometalated ligands) were designed and synthesized. These complexes were tested for attaching a protein by coordinating to H/X (HisMet, HisHis, and HisCys) that are separated by i and i+4 in α-helix. Replacement of the two labile water ligands in the iridium(III) complex by a protein HisHis pair increases the luminescent intensity up to over 100 folds. This labeling approach has been demonstrated in a highly specific and efficient manner in a number of proteins, and it is also feasible for labeling target proteins in cell lysates.

Keywords: luminescent labeling of proteins; non-emissive iridium(III) complexes; protein structure; site-specific labeling of proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Iridium* / chemistry
  • Luminescence*

Substances

  • Iridium