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

Chem. - Eur. J. 2015, 21, 12188-12193, 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.

Salmain, M.

Dalton Trans. 2014, 43, 5482-5489, 10.1039/c3dt53253d

Protein hybrids resulting from the supramolecular anchoring to bovine β-lactoglobulin of fatty acid-derived Rh(iii) diimine complexes catalysed the asymmetric transfer hydrogenation of trifluoroacetophenone with up to 32% ee.

Schwaneberg, U.

ACS Catal. 2018, 8, 2611-2614, 10.1021/acscatal.7b04369

Whole cell catalysis is, in many cases, a prerequisite for the cost-effective production of chemicals by biotechnological means. Synthetic metal catalysts for bioorthogonal reactions can be inactivated within cells due to abundant thiol derivatives. Here, a cell surface display-based whole cell biohybrid catalyst system (termed ArMt bugs) is reported as a generally applicable platform to unify cost-effective whole cell catalysis with biohybrid catalysis. An inactivated esterase autotransporter is employed to display the nitrobindin protein scaffold with a Rh catalyst on the E. coli surface. Stereoselective polymerization of phenylacetylene yielded a high turnover number (TON) (39 × 106 cell–1) for the ArMt bugs conversion platform.

Salmain, M.

Chem. Commun. 2012, 48, 11984, 10.1039/c2cc36980j

Artificial metalloproteins resulting from the embedding of half-sandwich Ru(II)/Rh(III) fatty acid derivatives within β-lactoglobulin catalysed the asymmetric transfer hydrogenation of trifluoroacetophenone with modest to good conversions and fair ee's.