Ricoux, R.

Chem. Eur. J. 2020, 26, 14929-14937, 10.1002/chem.202002434

A novel inducible artificial metalloenzyme obtained by covalent attachment of a manganese(III)-tetraphenylporphyrin (MnTPP) to the artificial bidomain repeat protein, (A3A3′)Y26C, is reported. The protein is part of the αRep family. The biohybrid was fully characterized by MALDI-ToF mass spectrometry, circular dichroism and UV/Vis spectroscopies. The peroxidase and monooxygenase activities were evaluated on the original and modified scaffolds including those that have a) an additional imidazole, b) a specific αRep bA3-2 that is known to induce the opening of the (A3A3′) interdomain region and c) a derivative of the αRep bA3-2 inducer extended with a His6-Tag (His6-bA3-2). Catalytic profiles are highly dependent on the presence of co-catalysts with the best activity obtained with His6-bA3-2. The entire mechanism was rationalized by an integrative molecular modeling study that includes protein–ligand docking and large-scale molecular dynamics. This constitutes the first example of an entirely artificial metalloenzyme with inducible peroxidase and monooxygenase activities, reminiscent of allosteric regulation of natural enzymatic pathways.

Klein Gebbink, R.J.M.; van Koten, G.

Tetrahedron Lett. 2011, 52, 1601-1604, 10.1016/j.tetlet.2011.01.106

The preparation of a heterogeneous bifunctional catalytic system, combining the catalytic properties of an organometallic catalyst (racemization) with those of an enzyme (enantioselective acylation) is described. A novel ruthenium phosphonate inhibitor was synthesized and covalently anchored to a lipase immobilized on a solid support (CALB, Novozym® 435). The immobilized bifunctional catalytic system showed activity in both racemization of (S)-1-phenylethanol and selective acylation of 1-phenylethanol.

Klein Gebbink, R.J.M.

Chem. Commun. 2015, 51, 6792-6795, 10.1039/c4cc09700a

A Rh(NHC) phosphonate complex reacts with the lipases cutinase and Candida antarctica lipase B resulting in the first (soluble) artificial metalloenzymes formed by covalent active site-directed hybridization. When compared to unsupported complexes, these new robust hybrids show enhanced chemoselectivity in the (competitive) hydrogenation of olefins over ketones.

Filice, M.; Palomo, J.M.

Adv. Synth. Catal. 2015, 357, 2687-2696, 10.1002/adsc.201500014

A p‐nitrophenylphosphonate palladium pincer was synthesized and selectively inserted by irreversible attachment on the catalytic serine of different commercial lipases with good to excellent yields in most cases. Among all, lipase from Candida antarctica B (CAL‐B) was the best modified enzyme. The artificial metalloenzyme CAL‐B‐palladium (Pd) catalyst was subsequently immobilized on different supports and by different orienting strategies. The catalytic properties of the immobilized hybrid catalysts were then evaluated in two sets of Heck cross‐coupling reactions under different conditions. In the first reaction between iodobenzene and ethyl acrylate, the covalent immobilized CAL‐B‐Pd catalyst resulted to be the best one exhibiting quantitative production of the Heck product at 70 °C in dimethylformamide (DMF) with 25% water and particularly in pure DMF, where the soluble Pd pincer was completely inactive. A post‐immobilization engineering of catalyst surface by its hydrophobization enhanced the activity. The selectivity properties of the best hybrid catalyst were then assessed in the asymmetric Heck cross‐coupling reaction between iodobenzene and 2,3‐dihydrofuran retrieving excellent results in terms of stereo‐ and enantioselectivity.