Biomimetic Modeling of Copper Complexes: A Study of Enantioselective Catalytic Oxidation on D-(+)-Catechin and L-( − )-Epicatechin with Copper Complexes

The biomimetic catalytic oxidations of the dinuclear and trinuclear copper(II) complexes versus two catechols, namely, D-(+)-catechin and L-( − )-epicatechin to give the corresponding quinones are reported. The unstable quinones were trapped by the nucleophilic reagent, 3-methyl-2-benzothiazolinone hydrazone (MBTH), and have been calculated the molar absorptivities of the different quinones. The catalytic efficiency is moderate, as inferred by kinetic constants, but the complexes exhibit significant enantio-differentiating ability towards the catechols, albeit for the dinuclear complexes, this enantio-differentiating ability is lower. In all cases, the preferred enantiomeric substrate is D-(+)-catechin to respect the other catechol, because of the spatial disposition of this substrate

Controlling stereoselectivity by enzymatic and chemical means to access enantiomerically pure (1S,3R)-1-benzyl-2,3-dimethyl-1,2,3,4-tetrahydroisoquinoline derivatives

A chemoenzymatic strategy for the synthesis of enantiomerically pure novel alkaloids (1S,3R)- 1-benzyl-2,3-dimethyl-1,2,3,4-tetrahydroisoquinolines is presented. The key steps are the biocatalytic stereoselective reductive amination of substituted 1-phenylpropan-2-one derivatives to yield chiral amines employing microbial x-transaminases, and the diastereoselective reduction of a Bischler– Napieralski imine intermediate by catalytic hydrogenation in the presence of palladium on charcoal, leading exclusively to the desired cis-isomerFil: Orden, Alejandro Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Investigaciones en Tecnología Química; Argentina;Fil: Schrittwieser, Joerg H.. University of Graz. Department of Chemistry, Organic and Bioorganic Chemistry; Austria;Fil: Resch, Verena. University of Graz. Department of Chemistry, Organic and Bioorganic Chemistry; Austria;Fil: Mutti, Francesco G.. University of Graz. Department of Chemistry, Organic and Bioorganic Chemistry; Austria;Fil: Kroutil, Wolfgang. University of Graz. Department of Chemistry, Organic and Bioorganic Chemistry; Austria

Recyclable and Robust Optical Nanoprobes with Engineered Enzymes for Sustainable Serodiagnostics

Recyclable fluorescence assays that can be stored at room temperature would greatly benefit biomedical diagnostics by bringing sustainability and cost-efficiency, especially for point-of-care serodiagnostics in developing regions. Here, a general strategy is proposed to generate recyclable fluorescent probes by using engineered enzymes with enhanced thermo-/chemo-stability, which maintains an outstanding serodiagnostic performance (accuracy >95%) after 10 times of recycling as well as after storage at elevated temperatures (37 °C for 10 days). With these three outstanding properties, recyclable fluorescent probes can be designed to detect various biomarkers of clinical importance by using different enzymes

Multi‐Channel Lanthanide Nanocomposites for Customized Synergistic Treatment of Orthotopic Multi‐Tumor Cases

Simultaneous photothermal ablation of multiple tumors is limited by unpredictable photo-induced apoptosis, caused by individual intratumoral differences. Here, a multi-channel lanthanide nanocomposite was used to achieve tailored synergistic treatment of multiple subcutaneous orthotopic tumors under non-uniform whole-body infrared irradiation prescription. The nanocomposite reduces intratumoral glutathione by simultaneously activating the fluorescence and photothermal channels. The fluorescence provides individual information on different tumors, allowing customized prescriptions to be made. This enables optimal induction of hyperthermia and dosage of chemo drugs, to ensure treatment efficacy, while avoiding overtherapy. With an accessional therapeutic laser system, customized synergistic treatment of subcutaneous orthotopic cancer cases with multiple tumors is possible with both high efficacy and minimized side effects

Customized Enhancement of Thermal Sensitivity of Tumors at Different Subcutaneous Depths by Multichannel Lanthanide Nanocomposites

The photothermal therapeutic effect on tumors located at different subcutaneous depths varies due to the attenuation of light by tissue. Here, based on the wavelength-dependent optical attenuation properties of tissues, the tumor depth is assessed using a multichannel lanthanide nanocomposite. A zeolitic imidazolate framework (ZIF-8)-coated nanocomposite is able to deliver high amounts of the hydrophilic heat shock protein 90 inhibitor epigallocatechin gallate through a hydrogen-bonding network formed by the encapsulated highly polarized polyoxometalate guest. It is superior to both bare and PEGylated ZIF-8 for drug delivery. With the assessment of tumor depth and accumulated amount of nanocomposite by fluorescence, an irradiation prescription can be customized to release sufficient HSP90 inhibitor and generate heat for sensitized photothermal treatment of tumors, which not only ensured therapeutic efficacy but also minimized damage to the surrounding tissues

Motion for a Resolution tabled by Mr Barbi, Mr Vergeer, Mr Pedini, Mr Langes, Mr Penders, Mr Marck, Mrs Lenz, Mrs Walz, Mr Alber and Mrs Lentz-Cornette on behalf of the Group of the European People's Party (C-D Group) pursuant to Rule 47 of the Rules of Procedure on Nicaragua, Working Documents 1983-1984, Document 1-237/83, 26 April 1983

Peroxygenases offer an attractive means to address challenges in selective oxyfunctionalization chemistry. Despite this, their application in synthetic chemistry remains challenging due to their facile inactivation by the stoichiometric oxidant H2O2. Often atom-inefficient peroxide generation systems are required, which show little potential for large-scale implementation. Here, we show that visible-light-driven, catalytic water oxidation can be used for in situ generation of H2O2 from water, rendering the peroxygenase catalytically active. In this way, the stereoselective oxyfunctionalization of hydrocarbons can be achieved by simply using the catalytic system, water and visible light.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.BT/BiocatalysisBN/Greg Bokinsky La

Alkene Cleavage Catalysed by Heme and Nonheme Enzymes: Reaction Mechanisms and Biocatalytic Applications

The oxidative cleavage of alkenes is classically performed by chemical methods, although they display several drawbacks. Ozonolysis requires harsh conditions (−78°C, for a safe process) and reducing reagents in a molar amount, whereas the use of poisonous heavy metals such as Cr, Os, or Ru as catalysts is additionally plagued by low yield and selectivity. Conversely, heme and nonheme enzymes can catalyse the oxidative alkene cleavage at ambient temperature and atmospheric pressure in an aqueous buffer, showing excellent chemo- and regioselectivities in certain cases. This paper focuses on the alkene cleavage catalysed by iron cofactor-dependent enzymes encompassing the reaction mechanisms (in case where it is known) and the application of these enzymes in biocatalysis

Resonance Neutron Capture in 60Ni below 450 keV.

Abstract not availableJRC.D-Institute for Reference Materials and Measurements (Geel

Synthesis of enantiomerically pure alcohols and amines: Via biocatalytic deracemisation methods

Deracemisation via chemo-enzymatic or multi-enzymatic approaches is the optimum substitute for kinetic resolution, which suffers from the limitation of a theoretical maximum 50% yield albeit high enantiomeric excess is attainable. This review covers the recent progress in various deracemisation approaches applied to the synthesis of enantiomerically pure alcohols and amines, such as (1) dynamic kinetic resolution, (2) cyclic deracemisation, (3) linear deracemisation (including stereoinversion) and (4) enantioconvergent methods.BT/Biocatalysi

Unlocking Catalytic Diversity of a Formate Dehydrogenase: Formamide Activity for NADPH Regeneration and Amine Supply for Asymmetric Reductive Amination

The formate dehydrogenase (FDH) from Candida boidinii is a well-studied and applied enzyme for NADH regeneration in various reactions. As many oxidoreductases require NADPH, FDH mutants were created with shifted cofactor specificity toward NADP+. However, less effort was made to elucidate the substrate specificity for the hydride donors. Here, we report the FDH-catalyzed cleavage of formamide (F) and derivatives thereof into CO2 and amines, while regenerating the cofactors NADH and NADPH. Wild-type FDH and the NADP+-accepting variant FDH C23S/D195Q/Y196R/Q197N (FDH M5) showed both activity with 10% (v/v) F, N-methylformamide (MF), and N,N-dimethylformamide of 80, 67, and 4.5 mU/mg, and 4.9, 4.7, and 0.5 mU/mg, respectively. In silico docking and molecular dynamics simulation gave insights into substrate binding, indicating an altered binding conformation. NADP+-accepting variants were utilized in a cascade set up for the reductive amination of cyclohexanone by means of reductive aminase from Aspergillus oryzae with MF as hydride and amine donor, thereby reaching conversion rates of 72% in a whole cell approach. This work broadens the applicability of FDHs in biocatalysis