In metalloenzymes, histidine is typically assumed to bind to metals via a nitrogen atom. We investigated the carbon-bonding mode in the small Cu-protein azurin from P. aeruginosa and, for the first time, demonstrated the implication of such C-bonding by using an N-heterocyclic carbene as a surrogate for C-bound histidine.
We obtained evidence that replacing a histidine, with a carbene ligand substantially alters the redox properties of the metal center.

This work was carried out in the group of Prof. Dr. Martin Albrecht.

References:

• M. Planchestainer, N. Segaud, M. Shanmugam, J. McMaster, F. Paradisi, M. Albrecht;
  "Carbene in Cupredoxin Protein Scaffolds: Replacement of a Histidine Ligand in the Active Site Substantially Alters Copper Redox Properties"
  Angew. Chem. Int. Ed., 2018, 57(33), 10677-10682; doi:10.1002/anie.201807168.