Carbene in Cupredoxin Protein Scaffolds: Replacement of a Histidine Ligand in the Active Site Substantially Alters Copper Redox Properties |
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| Authors: | Dr Matteo Planchestainer Dr Nathalie Segaud Dr Muralidharan Shanmugam Prof Jonathan McMaster Prof Francesca Paradisi Prof Martin Albrecht |
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| Institution: | 1. School of Chemistry, University of Nottingham, Nottingham, UK;2. Department of Chemistry & Biochemistry, Universit?t Bern, Bern, Switzerland;3. Manchester Institute of Biotechnology, University of Manchester, Manchester, UK |
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| Abstract: | N‐heterocyclic carbene (NHC) ligands have had a major impact in homogeneous catalysis, however, their potential role in biological systems is essentially unexplored. We replaced a copper‐coordinating histidine (His) in the active site of the redox enzyme azurin with exogenous dimethyl imidazolylidene. This NHC rapidly restores the type‐1 Cu center, with spectroscopic properties (EPR, UV/Vis) that are identical to those from N‐coordination of the His in the wild type. However, the introduction of the NHC markedly alters the redox potential of the metal, which is a key functionality of this blue copper protein. These results suggest that C‐bonding for histidine is plausible and a potentially relevant bonding mode of redox‐active metalloenzymes in their (transient) active states. |
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| Keywords: | ligand bonding mode electron transfer histidine metalloenzymes N-heterocyclic carbenes |
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