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Redox-switchable siderophore anchor enables reversible artificial metalloenzyme assembly

2018; Nature Portfolio; Volume: 1; Issue: 9 Linguagem: Inglês

10.1038/s41929-018-0124-3

2520-1158

Daniel J. Raines, Justin E. Clarke, E.V. Blagova, E.J. Dodson, Keith S. Wilson, Anne‐Kathrin Duhme‐Klair,

Electrocatalysts for Energy Conversion

Artificial metalloenzymes that contain protein-anchored synthetic catalysts are attracting increasing interest. An exciting, but still unrealized advantage of non-covalent anchoring is its potential for reversibility and thus component recycling. Here we present a siderophore–protein combination that enables strong but redox-reversible catalyst anchoring, as exemplified by an artificial transfer hydrogenase (ATHase). By linking the iron(iii)-binding siderophore azotochelin to an iridium-containing imine-reduction catalyst that produces racemic product in the absence of the protein CeuE, but a reproducible enantiomeric excess if protein bound, the assembly and reductively triggered disassembly of the ATHase was achieved. The crystal structure of the ATHase identified the residues involved in high-affinity binding and enantioselectivity. While in the presence of iron(iii), the azotochelin-based anchor binds CeuE with high affinity, and the reduction of the coordinated iron(iii) to iron(ii) triggers its dissociation from the protein. Thus, the assembly of the artificial enzyme can be controlled via the iron oxidation state. Artificial metalloenzymes can combine the scope of synthetic catalysts with the selectivity provided by the protein scaffold, but recycling of the single components is challenging. This work provides a methodology for controlling assembly and disassembly of an artificial metalloenzyme.