Niemeyer, C.M.

Chem. - Asian J. 2009, 4, 1064-1069, 10.1002/asia.200900082

A hybrid myoglobin, containing a single‐stranded DNA anchor and a redox‐active ruthenium moiety tethered to the heme center can be used as a photocatalyst. The catalyst can be selectively immobilized on a surface‐bound complementary DNA molecule and thus readily recycled from complex reaction mixtures. This principle may be applied to a range of heme‐dependent enzymes allowing the generation of novel light‐triggered photocatalysts. Photoactivatable myoglobin containing a DNA oligonucleotide as a structural anchor was designed by using the reconstitution of artificial heme moieties containing Ru3+ ions. This semisynthetic DNA–enzyme conjugate was successfully used for the oxidation of peroxidase substrates by using visible light instead of H2O2 for the activation. The DNA anchor was utilized for the immobilization of the enzyme on the surface of magnetic microbeads. Enzyme activity measurements not only indicated undisturbed biofunctionality of the tethered DNA but also enabled magnetic separation‐based enrichment and recycling of the photoactivatable biocatalyst.

Fruk, L.; Niemeyer, C.M.

Croat. Chem. Acta 2011, 84, 269-275, 10.5562/cca1828

A bimetallic heme-DNA cofactor, containing an iron and a copper center, was synthesized for the design of novel hybrid catalysts for stereoselective synthesis. The cofactor was used for the reconstitution of apo-myoglobin. Both the cofactor alone and its myoglobin adduct were used to catalyze a model Diels Alder reaction. Stereoselectivity of this conversion was analyzed by chiral HPLC. Reactions carried out in the presence of myoglobin-heme-Cu-DNA catalyst showed greater product conversion and stereoselectivity than those carried out with the heme-Cu-DNA cofactor. This observation suggested that the protein shell plays a significant role in the catalytic conversion.

Salmain, M.; Thorimbert, S.

Eur. J. Inorg. Chem. 2017, 2017, 3622-3634, 10.1002/ejic.201700365

Several prochiral NCN‐pincer complexes of palladium(II), with hemilabile ligands and a long aliphatic chain, were synthesized and characterized spectroscopically. In some of the complexes, the presence of two different substituents on the N donor atoms made them stereogenic, so that they were isolated as a mixture of diastereoisomers, which could be differentiated by 1H NMR spectroscopy. Binding of some of these complexes to bovine β‐lactoglobin by insertion within its inner cavity was theoretically investigated by molecular‐docking simulations and was experimentally confirmed by CD spectroscopy. Adjunction of H‐bond donor substituents on the ligand framework gave more‐stable supramolecular protein–complex assemblies. These constructs were shown to catalyze aldol condensation reactions in aqueous media, affording, in some cases, the less‐favorable cis product. Since the corresponding complexes exclusively gave the trans product in the absence of β‐lactoglobulin, this unusual diastereoselectivity was ensued by the second sphere of coordination brought by the protein host.