Bäckvall, J.E.; Diéguez, M.; Pàmies, O.

Adv. Synth. Catal. 2015, 357, 1567-1586, 10.1002/adsc.201500290

Artificial metalloenzymes combine the excellent selective recognition/binding properties of enzymes with transition metal catalysts, and therefore many asymmetric transformations can benefit from these entities. The search for new successful strategies in the construction of metal‐enzyme hybrid catalysts has therefore become a very active area of research. This review discusses all the developed strategies and the latest advances in the synthesis and application in asymmetric catalysis of artificial metalloenzymes with future directions for their design, synthesis and application (Sections 2–4). Finally, advice is presented (to the non‐specialist) on how to prepare and use artificial metalloenzymes (Section 5).

Sheldon, R.A.

Chem. Commun. 1998, 1891-1892, 10.1039/a804702b

Phytase (E.C. 3.1.3.8), which in vivo mediates the hydrolysis of phosphate esters, catalyses the enantioselective oxidation of thioanisole with H2O2, both in the presence and absence of vanadate ion, affording the S-sulfoxide in up to 66% ee at 100% conversion.

Kim, H.M.; Lee, H.S.

Biomacromolecules 2020, 21, 5021-5028, 10.1021/acs.biomac.0c01194

Many natural proteins function in oligomeric forms, which are critical for their sophisticated functions. The construction of protein assemblies has great potential for biosensors, enzyme catalysis, and biomedical applications. In designing protein assemblies, a critical process is to create protein–protein interaction (PPI) networks at defined sites of a target protein. Although a few methods are available for this purpose, most of them are dependent on existing PPIs of natural proteins to some extent. In this report, a metal-chelating amino acid, 2,2′-bipyridylalanine (BPA), was genetically introduced into defined sites of a monomeric protein and used to form protein oligomers. Depending on the number of BPAs introduced into the protein and the species of metal ions (Ni2+ and Cu2+), dimers or oligomers with different oligomerization patterns were formed by complexation with a metal ion. Oligomer sizes could also be controlled by incorporating two BPAs at different locations with varied angles to the center of the protein. When three BPAs were introduced, the monomeric protein formed a large complex with Ni2+. In addition, when Cu2+ was used for complex formation with the protein containing two BPAs, a linear complex was formed. The method proposed in this report is technically simple and generally applicable to various proteins with interesting functions. Therefore, this method would be useful for the design and construction of functional protein assemblies.

Sheldon, R.A.

Can. J. Chem. 2002, 80, 622-625, 10.1139/v02-082

The catalytic Zn2+ ion was extracted from thermolysin, which had been covalently bound to Eupergit C. The apo-enzyme incorporated the oxometallate anions MoO42–, SeO42–, and WO42– with partial restoration of the proteolytic activity. Tungstate thermolysin was moderately active in the sulfoxidation of thioanisole by hydrogen peroxide, whereas its activity towards phenylmercaptoacetophenone, which was designed to bind well in the active site of thermolysin, was much higher.

Sheldon, R.A.

Biotechnol. Bioeng. 2000, 67, 87-96, 10.1002/(SICI)1097-0290(20000105)67:1<87::AID-BIT10>3.0.CO;2-8

A semisynthetic peroxidase was designed by exploiting the structural similarity of the active sites of vanadium dependent haloperoxidases and acid phosphatases. Incorporation of vanadate ion into the active site of phytase (E.C. 3.1.3.8), which mediates in vivo the hydrolysis of phosphate esters, leads to the formation of a semisynthetic peroxidase, which catalyzes the enantioselective oxidation of prochiral sulfides with H2O2 affording the S‐sulfoxide, e.g. in 66% ee at 100% conversion for thioanisole. Under reaction conditions the semi‐synthetic vanadium peroxidase is stable for over 3 days with only a slight decrease in turnover frequency. Polar water‐miscible cosolvents, such as methanol, dioxane, and dimethoxyethane, can be used in concentrations of 30% (v/v) at a small penalty in activity and enantioselectivity. Among the transition metal oxoanions that are known to be potent inhibitors, only vanadate resulted in a semisynthetic peroxidase when incorporated into phytase. A number of other acid phosphatases and hydrolases were tested for peroxidase activity, when incorporated with vanadate ion. Phytases from Aspergillus ficuum, A. fumigatus, and A. nidulans, sulfatase from Helix pomatia, and phospholipase D from cabbage catalyzed enantioselective oxygen transfer reactions when incorporated with vanadium. However, phytase from A. ficuum was unique in also catalyzing the enantioselective sulfoxidation, albeit at a lower rate, in the absence of vanadate ion.

Sheldon, R.A.

Top. Catal. 2000, 13, 259-265, 10.1023/A:1009094619249

Approaches to the rational design of vanadium-based biocatalytic and biomimetic model systems as catalysts for enantioselective oxidations are reviewed. Incorporation of vanadate ion into the active site of phytase (E.C. 3.1.3.8), which in vivo mediates the hydrolysis of phosphate esters, afforded a relatively stable and inexpensive semi-synthetic peroxidase. It catalysed the enantioselective oxidation of prochiral sulfides with H2O2 affording the S-sulfoxide, e.g., in 68% ee at 100% conversion for thioanisole. Amongst the transition metal oxoanions that are known to be potent inhibitors of phosphatases, only vanadate resulted in a semi-synthetic peroxidase, when incorporated into phytase. In a biomimetic approach, vanadium complexes of chiral Schiff's base complexes were encapsulated in the super cages of a hydrophobic zeolite Y. Unfortunately, these ship-in-a-bottle complexes afforded only racemic sulfoxide in the catalytic oxidation of thioanisole with H2O2.