TY - JOUR A1 - Kaufmann, Hans Paul A1 - Duffus, Benjamin R. A1 - Mitrova, Biljana A1 - Iobbi-Nivol, Chantal A1 - Teutloff, Christian A1 - Nimtz, Manfred A1 - Jaensch, Lothar A1 - Wollenberger, Ulla A1 - Leimkühler, Silke T1 - Modulating the Molybdenum Coordination Sphere of Escherichia coli Trimethylamie N-Oxide Reductase JF - Biochemistry N2 - The well-studied enterobacterium Escherichia coli present in the human gut can reduce trimethylamine N-oxide (TMAO) to trimethylamine during anaerobic respiration. The TMAO reductase TorA is a monomeric, bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor-containing enzyme that belongs to the dimethyl sulfoxide reductase family of molybdoenzymes. We report on a system for the in vitro reconstitution of TorA with molybdenum cofactors (Moco) from different sources. Higher TMAO reductase activities for TorA were obtained when using Moco sources containing a sulfido ligand at the molybdenum atom. For the first time, we were able to isolate functional bis-MGD from Rhodobacter capsulatus formate dehydrogenase (FDH), which remained intact in its isolated state and after insertion into apo-TorA yielded a highly active enzyme. Combined characterizations of the reconstituted TorA enzymes by electron paramagnetic resonance spectroscopy and direct electrochemistry emphasize that TorA activity can be modified by changes in the Mo coordination sphere. The combination of these results together with studies of amino acid exchanges at the active site led us to propose a novel model for binding of the substrate to the molybdenum atom of TorA. Y1 - 2018 U6 - https://doi.org/10.1021/acs.biochem.7b01108 SN - 0006-2960 VL - 57 IS - 7 SP - 1130 EP - 1143 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Kaufmann, Paul A1 - Duffus, Benjamin R. A1 - Teutloff, Christian A1 - Leimkühler, Silke T1 - Functional Studies on Oligotropha carboxidovorans Molybdenum-Copper CO Dehydrogenase Produced in Escherichia coli JF - Biochemistry N2 - The Mo/Cu-dependent CO dehydrogenase (CODH) from Oligotropha carboxidovorans is an enzyme that is able to catalyze both the oxidation of CO to CO2 and the oxidation of H-2 to protons and electrons. Despite the close to atomic resolution structure (1.1 angstrom), significant uncertainties have remained with regard to the reaction mechanism of substrate oxidation at the unique Mo/Cu center, as well as the nature of intermediates formed during the catalytic cycle. So far, the investigation of the role of amino acids at the active site was hampered by the lack of a suitable expression system that allowed for detailed site-directed mutagenesis studies at the active site. Here, we report on the establishment of a functional heterologous expression system of O. carboxidovorans CODH in Escherichia coli. We characterize the purified enzyme in detail by a combination of kinetic and spectroscopic studies and show that it was purified in a form with characteristics comparable to those of the native enzyme purified from O. carboxidovorans. With this expression system in hand, we were for the first time able to generate active-site variants of this enzyme. Our work presents the basis for more detailed studies of the reaction mechanism for CO and H-2 oxidation of Mo/Cu-dependent CODHs in the future. Y1 - 2018 U6 - https://doi.org/10.1021/acs.biochem.8b00128 SN - 0006-2960 VL - 57 IS - 19 SP - 2889 EP - 2901 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Giulbudagian, Michael A1 - Hönzke, Stefan A1 - Bergueiro, Julián A1 - Işık, Doğuş A1 - Schumacher, Fabian A1 - Saeidpour, Siavash A1 - Lohan, Silke A1 - Meinke, Martina A1 - Teutloff, Christian A1 - Schäfer-Korting, Monika A1 - Yealland, Guy A1 - Kleuser, Burkhard A1 - Hedtrich, Sarah A1 - Calderón, Marcelo T1 - Enhanced topical delivery of dexamethasone by beta-cyclodextrin decorated thermoresponsive nanogels JF - Nanoscale N2 - Highly hydrophilic, responsive nanogels are attractive as potential systems for the topical delivery of bioactives encapsulated in their three-dimensional polymeric scaffold. Yet, these drug carrier systems suffer from drawbacks for efficient delivery of hydrophobic drugs. Addressing this, β-cyclodextrin (βCD) could be successfully introduced into the drug carrier systems by exploiting its unique affinity toward dexamethasone (DXM) as well as its role as topical penetration enhancer. The properties of βCD could be combined with those of thermoresponsive nanogels (tNGs) based on dendritic polyglycerol (dPG) as a crosslinker and linear thermoresponsive polyglycerol (tPG) inducing responsiveness to temperature changes. Electron paramagnetic resonance (EPR) studies localized the drug within the hydrophobic cavity of βCD by differences in its mobility and environmental polarity. In fact, the fabricated carriers combining a particulate delivery system with a conventional penetration enhancer, resulted in an efficient delivery of DXM to the epidermis and the dermis of human skin ex vivo (enhancement compared to commercial DXM cream: ∼2.5 fold in epidermis, ∼30 fold in dermis). Furthermore, DXM encapsulated in βCD tNGs applied to skin equivalents downregulated the expression of proinflammatory thymic stromal lymphopoietin (TSLP) and outperformed a commercially available DXM cream. Y1 - 2017 U6 - https://doi.org/10.1039/c7nr04480a SN - 2040-3364 SN - 2040-3372 VL - 10 IS - 1 SP - 469 EP - 479 PB - Royal Society of Chemistry CY - Cambridge ER -