Preparation and Characterization of Enzyme Compartments in UV-Cured Polyurethane-Based Materials and Their Application in Enzymatic Reactions

The preparation and characterization of UV-cured polyurethane-based materials for the mild inclusion immobilization of enzymes was investigated. Full curing of the polymer precursor/enzyme solution mixture was realized by a short irradiation with UV-light at ambient temperatures. The included aqueous enzyme solution remains highly dispersed in the polymer material with an even size distribution throughout the polymer material. The presented concept provides stable enzyme compartments which were applied for an alcohol dehydrogenase-catalyzed reduction reaction in organic solvents. Cofactor regeneration was achieved by a substrate-coupled approach via 2-propanol or an enzyme-coupled approach by a glucose dehydrogenase. This reaction concept can also be used for a simultaneous application of contrary biocatalytic reaction conditions within an enzymatic cascade reaction. Independent polymer-based reaction compartments were provided for two incompatible enzymatic reaction systems (alcohol dehydrogenase and hydroxynitrile lyase), while the relevant reactants diffuse between the applied compartments

Crystallization assisted dynamic kinetic resolution for the synthesis of (R)-beta-methylphenethylamine

Belov F, Gazizova A, Bork H, Gröger H, von Langermann J. Crystallization assisted dynamic kinetic resolution for the synthesis of (R)-beta-methylphenethylamine. ChemBioChem . 2024.This study explores a combination of the concept of enantioselective enzymatic synthesis of beta-chiral amines through transamination with in situ product crystallization (ISPC) to overcome product inhibition. Using 2-phenylpropanal as a readily available and easily racemizing substrate of choice, (R)-beta-methylphenethylamine ((R)-2-phenylpropan-1-amine) concentrations of up to 250 mM and enantiomeric excesses of up to 99 % are achieved when using a commercially available transaminase from Ruegeria pomeroyi in a fed-batch based dynamic kinetic resolution reaction on preparative scale. The source of substrate decomposition during the reaction is also investigated and the resulting unwanted byproduct formation is successfully reduced to insignificant levels. © 2024 Wiley‐VCH GmbH

Synthesis of Cyclic Carbonates Catalyzed by CaI₂–Et₃N and Studies on Their Biocatalytic Kinetic Resolution

Herein, we report a simple catalytic system consisting of CaI2 in combination with Et3N as a ligand for the efficient cycloaddition of CO2 to a variety of epoxides. Terminal (bio-based) carbonates were obtained under mild conditions (23 °C, 1 bar CO2 pressure) in excellent yields up to 97%. Under elevated temperature (70 °C) and higher CO2 pressure (10 bar), even challenging internal epoxides were converted, leading to the desired carbonates in yields up to 90%. 1H NMR experiments indicated the in situ coordination of the amine to the Lewis acidic calcium center as well as the activation of the epoxide. Furthermore, the enzymatic kinetic resolution of seven cyclic carbonates using readily available pig liver esterase was investigated. Styrene carbonate proved to be the most suitable substrate for the kinetic resolution, leading to (R)-styrene carbonate in 99% ee

Recombinant pig liver esterase-catalyzed synthesis of (1S,4R)-4-hydroxy-2-cyclopentenyl acetate combined with subsequent enantioselective crystallization

The recombinant pig liver esterase catalyzed hydrolysis of cis-1,4-diacetoxy-2-cyclopentene forming (1S,4R)-4-hydroxy-2-cyclopentenyl acetate was investigated and realized at preparative scale. Relevant reaction conditions were examined and optimized to achieve full conversion with an enantiomeric excess of about 86% ee. Enantiopure product was then obtained after enantioselective crystallization, which required further studies of the solid phase behavior, including its binary melting point phase diagram

The phase behavior and crystallization of 2-chloromandelic acid: The crystal structure of the pure enantiomer and the behavior of its metastable conglomerate

Crystallization of racemic 2-chloromandelic acid yields a metastable conglomerate in addition to a more stable racemic compound. The crystal structure of the pure enantiomer is reported and the relative stability of the racemic compound and conglomerate was determined at both room temperature and the melting point. Crystallizations from melt and solution are shown to offer potential crystallization pathways to the conglomerate, provided crystallization of the racemic compound can be avoided. Copyright © 2011 American Chemical Society [accessed 27th May 2011

CCDC 778767: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures

Adsorbent-Based Downstream-Processing of the Decarboxylase-Based Synthesis of 2,6-Dihydroxy-4-methylbenzoic Acid

In this case study the regioselective enzymatic carboxylation of 3,5-dihydroxytoluene (orcinol) using the nonoxidative 2,3-dihydroxybenzoic acid decarboxylase from <i>Aspergillus oryzae</i> (2,3-DHBD_Ao), followed by an adsorbent-based downstream approach, has been investigated. The product 2,6-dihydroxy-4-methylbenzoic acid (DHMBA) was herein purified by an adsorption–desorption cycle and subsequently obtained with purities >99% without a full elimination of the excess bicarbonate from its reaction solution. Ten adsorbent resins were studied in respect of their ability to recover the product from the reaction solution, whereas the strong anion exchange resin Dowex 1x2 in its chloride form showed affinities >99%, even at bicarbonate concentrations of >3 mol·L^–1. Desorption from loaded resin was carried out by a 2 mol·L^–1 HCl/acetone mixture, followed by product crystallization during acetone evaporation. This presented concept does not require a final column preparation step and improves the overall atom efficiency of the biocatalytic reaction system

Recombinant Pig Liver Esterase-Catalyzed Synthesis of (1<i>S</i>,4<i>R</i>)‑4-Hydroxy-2-cyclopentenyl Acetate Combined with Subsequent Enantioselective Crystallization

The recombinant pig liver esterase catalyzed hydrolysis of <i>cis</i>-1,4-diacetoxy-2-cyclopentene forming (1<i>S</i>,4<i>R</i>)-4-hydroxy-2-cyclopentenyl acetate was investigated and realized at preparative scale. Relevant reaction conditions were examined and optimized to achieve full conversion with an enantiomeric excess of about 86% ee. Enantiopure product was then obtained after enantioselective crystallization, which required further studies of the solid phase behavior, including its binary melting point phase diagram