Gold-Catalyzed C-S Aryl-Group Transfer in Zinc Finger Proteins

Reaction of the Au-C N chelate [Au(bnpy)Cl₂ ] with the full-length zinc finger (ZnF; ZnCys₃ His) of HIV nucleocapsid protein NCp7 results in C-S aryl transfer from the Au^III organometallic species to a cysteine of the ZnF. The reaction is general and occurs even for finger 3 of the transcription factor Sp1, containing a ZnCys₂ His₂ coordination sphere. This reaction is the first demonstration of group transfer from a coordination compound to biologically important zinc fingers, and is especially noteworthy for the ZnCys₂ His₂ transcription factors. The work expands the corpus of organometallic species which can efficiently modify biomolecules through C-atom transfer. The electronic features of the gold compound leading to this unexpected reaction were explored by X-ray absorption spectroscopy.