Renaud, J.-L.; Ward, T. R.

Catal. Lett., 2016, 10.1007/s10562-015-1681-6

We report on the synthesis of biotinylated (cyclopentadienone)iron tricarbonyl complexes, the in situ generation of the corresponding streptavidin conjugates and their application in asymmetric hydrogenation of imines and ketones.

Mahy, J.-P.

Eur. J. Biochem., 1998, 10.1046/j.1432-1327.1998.2570121.x

The topology of the binding site has been studied for two monoclonal antibodies 13G10 and 14H7, elicited against iron(III)‐α,α,α,β‐meso‐tetrakis(ortho‐carboxyphenyl)porphyrin {α,α,α,β‐Fe[(o‐COOHPh)4‐porphyrin]}, and which exhibit in the presence of this α,α,α,β‐Fe[(o‐COOHPh)4‐porphyrin] cofactor a peroxidase activity. A comparison of the dissociation constants of the complexes of 13G10 and 14H7 with various tetra‐aryl‐substituted porphyrin has shown that : (a) the central iron(III) atom of α,α,α,β‐Fe[(o‐COOHPh)4‐porphyrin] is not recognized by either of the two antibodies; and (b) the ortho‐carboxylate substituents of the meso‐phenyl rings of α,α,α,β‐Fe[(o‐COOHPh)4‐porphyrin] are essential for the recognition of the porphyrin by 13G10 and 14H7. Measurement of the dissociation constants for the complexes of 13G10 and 14H7 with the four atropoisomers of (o‐COOHPh)4‐porphyrinH2 as well as mono‐ and di‐ortho‐carboxyphenyl‐substituted porphyrins suggests that the three carboxylates in the α, α, β position are recognized by both 13G10 and 14H7 with the two in the α, β positions more strongly bound to the antibody protein. Accordingly, the topology of the active site of 13G10 and 14H7 has roughly two‐thirds of the α,α,α,β‐Fe[(o‐COOHPh)4‐porphyrin] cofactor inserted into the binding site of the antibodies, with one of the aryl ring remaining outside. Three of the carboxylates are bound to the protein but no amino acid residue acts as an axial ligand to the iron atom. Chemical modification of lysine, histidine, tryptophan and arginine residues has shown that only modification of arginine residues causes a decrease in both the binding of α,α,α,β‐Fe[(o‐COOHPh)4‐porphyrin] and the peroxidase activity of both antibodies. Consequently, at least one of the carboxylates of the hapten is bound to an arginine residue and no amino acids such as lysine, histidine or tryptophan participate in the catalysis of the heterolytic cleavage of the O‐O bond of H2O2. In addition, the amino acid sequence of both antibodies not only reveals the presence of arginine residues, which could be those involved in the binding of the carboxylates of the hapten, but also the presence of several amino acids in the complementary determining regions which could bind other carboxylates through a network of H bonds.

Lu, Y.

Science, 2018, 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.

Hayashi, T

Chem. Commun., 2011, 10.1039/c1cc11157d

The diiron carbonyl cluster is held by a native CXXC motif, which includes Cys14 and Cys17, in the cytochrome c sequence. It is found that the diiron carbonyl complex works well as a catalyst for H2 evolution. It has a TON of ∼80 over 2 h at pH 4.7 in the presence of a Ru-photosensitizer and ascorbate as a sacrificial reagent in aqueous media.

DeGrado, W. F.

Nat. Chem., 2012, 10.1038/NCHEM.1454

De novo proteins provide a unique opportunity to investigate the structure–function relationships of metalloproteins in a minimal, well-defined and controlled scaffold. Here, we describe the rational programming of function in a de novo designed di-iron carboxylate protein from the Due Ferri family. Originally created to catalyse the O2-dependent, two-electron oxidation of hydroquinones, the protein was reprogrammed to catalyse the selective N-hydroxylation of arylamines by remodelling the substrate access cavity and introducing a critical third His ligand to the metal-binding cavity. Additional second- and third-shell modifications were required to stabilize the His ligand in the core of the protein. These structural changes resulted in at least a 106-fold increase in the relative rate between the arylamine N-hydroxylation and hydroquinone oxidation reactions. This result highlights the potential for using de novo proteins as scaffolds for future investigations of the geometric and electronic factors that influence the catalytic tuning of di-iron active sites.

Roelfes, G.

Dalton Trans., 2017, 10.1039/C7DT00533D

Regulation of enzyme activity is essential in living cells. The rapidly increasing number of designer enzymes with new-to-nature activities makes it necessary to develop novel strategies for controlling their catalytic activity. Here we present the development of a metal ion regulated artificial metalloenzyme created by combining two anchoring strategies, covalent and supramolecular, for introducing a regulatory and a catalytic site, respectively. This artificial metalloenzyme is activated in the presence of Fe2+ ions, but only marginally in the presence of Zn2+.

DeGrado, W. F.; Lombardi, A.

Nat. Chem. Biol., 2009, 10.1038/nchembio.257

Here we report the de novo design and NMR structure of a four-helical bundle di-iron protein with phenol oxidase activity. The introduction of the cofactor-binding and phenol-binding sites required the incorporation of residues that were detrimental to the free energy of folding of the protein. Sufficient stability was, however, obtained by optimizing the sequence of a loop distant from the active site.

Banse, F.; Mahy, J.-P.

Chem. - Eur. J., 2015, 10.1002/chem.201501755

An artificial metalloenzyme based on the covalent grafting of a nonheme FeII polyazadentate complex into bovine β‐lactoglobulin has been prepared and characterized by using various spectroscopic techniques. Attachment of the FeII catalyst to the protein scaffold is shown to occur specifically at Cys121. In addition, spectrophotometric titration with cyanide ions based on the spin‐state conversion of the initial high spin (S=2) FeII complex into a low spin (S=0) one allows qualitative and quantitative characterization of the metal center’s first coordination sphere. This biohybrid catalyst activates hydrogen peroxide to oxidize thioanisole into phenylmethylsulfoxide as the sole product with an enantiomeric excess of up to 20 %. Investigation of the reaction between the biohybrid system and H2O2 reveals the generation of a high spin (S=5/2) FeIII(η2‐O2) intermediate, which is proposed to be responsible for the catalytic sulfoxidation of the substrate.

Roelfes, G.

Angew. Chem., Int. Ed., 2018, 10.1002/anie.201802946

Cavazza, C.; Ménage, S.

Angew. Chem., Int. Ed., 2014, 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.

Green, A. P.; Hilvert, D.

J. Am. Chem. Soc., 2018, 10.1021/jacs.7b12621

Lombardi, A.; Nastri, F.

Int. J. Mol. Sci., 2018, 10.3390/ijms19102896

Jarvis, A. G.

ACS Sustainable Chem. Eng., 2018, 10.1021/acssuschemeng.8b03568

Mahy, J.-P.

FEBS Lett., 1996, 10.1016/0014-5793(96)01006-X

Apfel, U.-P.; Happe, T.; Kurisu, G.

Chem. Sci., 2016, 10.1039/C5SC03397G

Schultz, P. G.

J. Am. Chem. Soc., 2008, 10.1021/ja804653f

Hilvert, D.

Nat. Catal., 2018, 10.1038/s41929-018-0105-6

Ménage, S.

J. Mol. Catal. A: Chem., 2016, 10.1016/j.molcata.2016.02.015

Hasegawa, J.-Y.; Lehnert, N.

J. Am. Chem. Soc., 2017, 10.1021/jacs.7b10154

Apfel, U.-P.; Happe, T.

Dalton Trans., 2017, 10.1039/C7DT03785F

Anderson, J. L. R.

Nat. Commun., 2017, 10.1038/s41467-017-00541-4

Mahy, J.-P.

Eur. J. Biochem., 2002, 10.1046/j.0014-2956.2001.02670.x

Mahy, J.-P.

J. Mol. Catal. A: Chem., 2010, 10.1016/j.molcata.2009.10.016

Cavazza, C.; Ménage, S.

J. Am. Chem. Soc., 2017, 10.1021/jacs.7b09343

Inorg. Chem., 2006, 10.1021/ic061130x

Golinelli-Pimpaneau, B.

Plos ONE, 2012, 10.1371/journal.pone.0051128

DeGrado, W. F.

Proc. Natl. Acad. Sci. U. S. A., 2004, 10.1073/pnas.0404387101

Ueno, T.

Proc. Natl. Acad. Sci. U. S. A., 2006, 10.1073/pnas.0510968103

Fasan, R.; Khare, S. D.

Proc. Natl. Acad. Sci. U. S. A., 2017, 10.1073/pnas.1708907114

Kaiser, E. T.

J. Am. Chem. Soc., 1987, 10.1021/ja00236a062