Lu, Y.

Science 2018, 361, 1098-1101, 10.1126/science.aat8474

Multielectron redox reactions often require multicofactor metalloenzymes to facilitate coupled electron and proton movement, but it is challenging to design artificial enzymes to catalyze these important reactions, owing to their structural and functional complexity. We report a designed heteronuclear heme-[4Fe-4S] cofactor in cytochrome c peroxidase as a structural and functional model of the enzyme sulfite reductase. The initial model exhibits spectroscopic and ligand-binding properties of the native enzyme, and sulfite reduction activity was improved—through rational tuning of the secondary sphere interactions around the [4Fe-4S] and the substrate-binding sites—to be close to that of the native enzyme. By offering insight into the requirements for a demanding six-electron, seven-proton reaction that has so far eluded synthetic catalysts, this study provides strategies for designing highly functional multicofactor artificial enzymes.

Cavazza, C.; Ménage, S.

Angew. Chem. Int. Ed. 2013, 52, 3922-3925, 10.1002/anie.201209021

The substrate for an artificial iron monooxygenase was selected by using docking calculations. The high catalytic efficiency of the reported enzyme for sulfide oxidation was directly correlated to the predicted substrate binding mode in the protein cavity, thus illustrating the synergetic effect of the substrate binding site, protein scaffold, and catalytic site.

Lewis, J.C.; Roux, B.

Angew. Chem. Int. Ed. 2021, 60, 23672-23677, 10.1002/anie.202107982

Artificial metalloenzymes (ArMs) are commonly used to control the stereoselectivity of catalytic reactions, but controlling chemoselectivity remains challenging. In this study, we engineer a dirhodium ArM to catalyze diazo cross-coupling to form an alkene that, in a one-pot cascade reaction, is reduced to an alkane with high enantioselectivity (typically >99 % ee) by an alkene reductase. The numerous protein and small molecule components required for the cascade reaction had minimal effect on ArM catalysis. Directed evolution of the ArM led to improved yields and E/Z selectivities for a variety of substrates, which translated to cascade reaction yields. MD simulations of ArM variants were used to understand the structural role of the cofactor on ArM conformational dynamics. These results highlight the ability of ArMs to control both catalyst stereoselectivity and chemoselectivity to enable reactions in complex media that would otherwise lead to undesired side reactions.