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29 pages, 8224 KiB

Open AccessReview

The Promising Role of Amine Transaminase Cascades in the Synthesis of Non-Canonical Amino Acids

by Najme Gord Noshahri and Jens Rudat

Processes 2024, 12(11), 2566; https://doi.org/10.3390/pr12112566 - 16 Nov 2024

Viewed by 1650

Amine transaminases (ATA) are critical players in producing non-canonical amino acids, essential building blocks in pharmaceuticals and fine chemicals. Significant progress has been made in discovering and engineering enzymes in this field, enhancing their use in organic synthesis. However, challenges such as co-factor [...] Read more.

Amine transaminases (ATA) are critical players in producing non-canonical amino acids, essential building blocks in pharmaceuticals and fine chemicals. Significant progress has been made in discovering and engineering enzymes in this field, enhancing their use in organic synthesis. However, challenges such as co-factor regeneration, substrate, and product inhibition remain significant limitations to widespread industrial enzyme application. (Chemo-)enzymatic cascades offer efficient and environmentally friendly pathways for synthesizing amino acids, reducing the need for multiple synthesis steps and saving the purification of intermediates. This review focuses specifically on the synthesis of non-canonical amino acids, emphasizing the use of enzymatic and chemoenzymatic cascades involving ATA. Full article

(This article belongs to the Special Issue Development, Modelling and Simulation of Biocatalytic Processes)

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14 pages, 3359 KiB

Open AccessArticle

Sustainable Chemoenzymatic Cascade Transformation of Corncob to Furfuryl Alcohol with Rice Husk-Based Heterogeneous Catalyst UST-Sn-RH

by Qizhen Yang, Zhengyu Tang, Jiale Xiong and Yucai He

Catalysts 2023, 13(1), 37; https://doi.org/10.3390/catal13010037 - 25 Dec 2022

Cited by 6 | Viewed by 1959

Abstract

Valorization of the abundant renewable lignocellulose through an efficient chemoenzymatic strategy to produce the furan-based platform compounds has raised great interest in recent years. In this work, a newly prepared sulfonated tin-loaded rice husk-based heterogeneous chemocatalyst UST-Sn-RH was utilized to transform corncob (75.0 [...] Read more.

Valorization of the abundant renewable lignocellulose through an efficient chemoenzymatic strategy to produce the furan-based platform compounds has raised great interest in recent years. In this work, a newly prepared sulfonated tin-loaded rice husk-based heterogeneous chemocatalyst UST-Sn-RH was utilized to transform corncob (75.0 g/L) into furfural (72.1 mM) at 170 °C for 30 min in an aqueous system. To upgrade furfural into furfuryl alcohol, whole cells of recombinant E. coli KPADH harboring alcohol dehydrogenase were employed to transform corncob-derived furfural into furfuryl alcohol at 30 °C and pH 7.5. In the established chemoenzymatic cascade process, corncob was efficiently transformed to furfuryl alcohol with a productivity of 0.304 g furfuryl alcohol/(g xylan in corncob). In general, biomass could be efficiently valorized into valuable furan-based chemicals in this tandem reaction with the chemocatalyst (bio-based UST-Sn-RH) and the biocatalyst (KPADH cell) in an aqueous system, which has potential application. Full article

(This article belongs to the Special Issue Biocatalytic Cascade Reactions)

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9 pages, 2034 KiB

Open AccessArticle

Efficient Synthesis of Biobased Furoic Acid from Corncob via Chemoenzymatic Approach

by Wei He, Yucai He and Jianren Ye

Processes 2022, 10(4), 677; https://doi.org/10.3390/pr10040677 - 30 Mar 2022

Cited by 4 | Viewed by 2375

Abstract

Valorization of lignocellulosic materials into value-added biobased chemicals is attracting increasing attention in the sustainable chemical industry. As an important building block, furoic acid has been commonly utilized to manufacture polymers, flavors, perfumes, bactericides, fungicides, etc. It is generally produced through the selective [...] Read more.

Valorization of lignocellulosic materials into value-added biobased chemicals is attracting increasing attention in the sustainable chemical industry. As an important building block, furoic acid has been commonly utilized to manufacture polymers, flavors, perfumes, bactericides, fungicides, etc. It is generally produced through the selective oxidation of furfural. In this study, we provide the results of the conversion of biomass-based xylose to furoic acid in a chemoenzymatic cascade reaction with the use of a heterogeneous chemocatalyst and a dehydrogenase biocatalyst. For this purpose, NaOH-treated waste shrimp shell was used as a biobased carrier to prepare high activity and thermostability of biobased solid acid catalysts (Sn-DAT-SS) for the dehydration of corncob-valorized xylose into furfural at 170 °C in 30 min. Subsequently, xylose-derived furfural and its derivative furfuryl alcohol were wholly oxidized into furoic acid with whole cells of E. coli HMFOMUT at 30 °C and pH 7.0. The productivity of furoic acid was 0.35 g furoic acid/(g xylan in corncob). This established chemoenzymatic process could be utilized to efficiently valorize biomass into value-added furoic acid. Full article

(This article belongs to the Section Sustainable Processes)

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10 pages, 1801 KiB

Open AccessArticle

Chemoenzymatic Conversion of Biomass-Derived D-Xylose to Furfuryl Alcohol with Corn Stalk-Based Solid Acid Catalyst and Reductase Biocatalyst in a Deep Eutectic Solvent–Water System

by Jianguang Liang, Li Ji, Jiarui He, Shuxin Tang and Yucai He

Processes 2022, 10(1), 113; https://doi.org/10.3390/pr10010113 - 6 Jan 2022

Cited by 9 | Viewed by 2100

Abstract

In this work, the feasibility of chemoenzymatically transforming biomass-derived D-xylose to furfuryl alcohol was demonstrated in a tandem reaction with SO₄²⁻/SnO₂-CS chemocatalyst and reductase biocatalyst in the deep eutectic solvent (DES)–water media. The high furfural yield (44.6%) [...] Read more.

In this work, the feasibility of chemoenzymatically transforming biomass-derived D-xylose to furfuryl alcohol was demonstrated in a tandem reaction with SO₄²⁻/SnO₂-CS chemocatalyst and reductase biocatalyst in the deep eutectic solvent (DES)–water media. The high furfural yield (44.6%) was obtained by catalyzing biomass-derived D-xylose (75.0 g/L) in 20 min at 185 °C with SO₄²⁻/SnO₂-CS (1.2 wt%) in DES ChCl:EG–water (5:95, v/v). Subsequently, recombinant E.coli CF cells harboring reductases transformed D-xylose-derived furfural (200.0 mM) to furfuryl alcohol in the yield of 35.7% (based on D-xylose) at 35 °C and pH 7.5 using HCOONa as cosubstrate in ChCl:EG–water. This chemoenzymatic cascade catalysis strategy could be employed for the sustainable production of value-added furan-based chemical from renewable bioresource. Full article

(This article belongs to the Section Sustainable Processes)

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13 pages, 3154 KiB

Open AccessArticle

Chemoenzymatic One-Pot Process for the Synthesis of Tetrahydroisoquinolines

by Andreas Sebastian Klein, Anna Christina Albrecht and Jörg Pietruszka

Catalysts 2021, 11(11), 1389; https://doi.org/10.3390/catal11111389 - 17 Nov 2021

Cited by 4 | Viewed by 3312

Abstract

1,2,3,4-Tetrahydroisoquinolines form a valuable scaffold for a variety of bioactive secondary metabolites and commercial pharmaceuticals. Due to the harsh or complex conditions of the conventional chemical synthesis of this molecular motif, alternative mild reaction pathways are in demand. Here we present an easy-to-operate [...] Read more.

1,2,3,4-Tetrahydroisoquinolines form a valuable scaffold for a variety of bioactive secondary metabolites and commercial pharmaceuticals. Due to the harsh or complex conditions of the conventional chemical synthesis of this molecular motif, alternative mild reaction pathways are in demand. Here we present an easy-to-operate chemoenzymatic one-pot process for the synthesis of tetrahydroisoquinolines starting from benzylic alcohols and an amino alcohol. We initially demonstrate the oxidation of 12 benzylic alcohols by a laccase/TEMPO system to the corresponding aldehydes, which are subsequently integrated in a phosphate salt mediated Pictet–Spengler reaction with m-tyramine. The reaction conditions of both individual reactions were analyzed separately, adapted to each other, and a straightforward one-pot process was developed. This enables the production of 12 1,2,3,4-tetrahydroisoquinolines with yields of up to 87% with constant reaction conditions in phosphate buffer and common laboratory glass bottles without the supplementation of any additives. Full article

(This article belongs to the Special Issue Biocatalytic Cascade Reactions)

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18 pages, 2703 KiB

Open AccessFeature PaperArticle

Two (Chemo)-Enzymatic Cascades for the Production of Opposite Enantiomers of Chiral Azidoalcohols

by Elia Calderini, Philipp Süss, Frank Hollmann, Rainer Wardenga and Anett Schallmey

Catalysts 2021, 11(8), 982; https://doi.org/10.3390/catal11080982 - 17 Aug 2021

Cited by 5 | Viewed by 3061

Abstract

Multi-step cascade reactions have gained increasing attention in the biocatalysis field in recent years. In particular, multi-enzymatic cascades can achieve high molecular complexity without workup of reaction intermediates thanks to the enzymes’ intrinsic selectivity; and where enzymes fall short, organo- or metal catalysts [...] Read more.

Multi-step cascade reactions have gained increasing attention in the biocatalysis field in recent years. In particular, multi-enzymatic cascades can achieve high molecular complexity without workup of reaction intermediates thanks to the enzymes’ intrinsic selectivity; and where enzymes fall short, organo- or metal catalysts can further expand the range of possible synthetic routes. Here, we present two enantiocomplementary (chemo)-enzymatic cascades composed of either a styrene monooxygenase (StyAB) or the Shi epoxidation catalyst for enantioselective alkene epoxidation in the first step, coupled with a halohydrin dehalogenase (HHDH)-catalysed regioselective epoxide ring opening in the second step for the synthesis of chiral aliphatic non-terminal azidoalcohols. Through the controlled formation of two new stereocenters, corresponding azidoalcohol products could be obtained with high regioselectivity and excellent enantioselectivity (99% ee) in the StyAB-HHDH cascade, while product enantiomeric excesses in the Shi-HHDH cascade ranged between 56 and 61%. Full article

(This article belongs to the Special Issue Biocatalytic Cascade Reactions (in vivo and in vitro))

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35 pages, 7765 KiB

Open AccessFeature PaperReview

Multicatalytic Hybrid Materials for Biocatalytic and Chemoenzymatic Cascades—Strategies for Multicatalyst (Enzyme) Co-Immobilization

by Aldo Araújo da Trindade Júnior, Yan Ferraz Ximenes Ladeira, Alexandre da Silva França, Rodrigo Octavio Mendonça Alves de Souza, Adolfo Henrique Moraes, Robert Wojcieszak, Ivaldo Itabaiana and Amanda Silva de Miranda

Catalysts 2021, 11(8), 936; https://doi.org/10.3390/catal11080936 - 31 Jul 2021

Cited by 19 | Viewed by 5562

Abstract

During recent decades, the use of enzymes or chemoenzymatic cascades for organic chemistry has gained much importance in fundamental and industrial research. Moreover, several enzymatic and chemoenzymatic reactions have also served in green and sustainable manufacturing processes especially in fine chemicals, pharmaceutical, and [...] Read more.

During recent decades, the use of enzymes or chemoenzymatic cascades for organic chemistry has gained much importance in fundamental and industrial research. Moreover, several enzymatic and chemoenzymatic reactions have also served in green and sustainable manufacturing processes especially in fine chemicals, pharmaceutical, and flavor/fragrance industries. Unfortunately, only a few processes have been applied at industrial scale because of the low stabilities of enzymes along with the problematic processes of their recovery and reuse. Immobilization and co-immobilization offer an ideal solution to these problems. This review gives an overview of all the pathways for enzyme immobilization and their use in integrated enzymatic and chemoenzymatic processes in cascade or in a one-pot concomitant execution. We place emphasis on the factors that must be considered to understand the process of immobilization. A better understanding of this fundamental process is an essential tool not only in the choice of the best route of immobilization but also in the understanding of their catalytic activity. Full article

(This article belongs to the Special Issue Catalysis and Biocatalysis for the Sustainable Valorization of Biomass)

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8 pages, 1128 KiB

Open AccessArticle

Chemo-Enzymatic Cascade for the Generation of Fragrance Aldehydes

by Daniel Schwendenwein, Anna K. Ressmann, Marcello Entner, Viktor Savic, Margit Winkler and Florian Rudroff

Catalysts 2021, 11(8), 932; https://doi.org/10.3390/catal11080932 - 30 Jul 2021

Cited by 9 | Viewed by 3510

Abstract

In this study, we present the synthesis of chiral fragrance aldehydes, which was tackled by a combination of chemo-catalysis and a multi-enzymatic in vivo cascade reaction and the development of a highly versatile high-throughput assay for the enzymatic reduction of carboxylic acids. We [...] Read more.

In this study, we present the synthesis of chiral fragrance aldehydes, which was tackled by a combination of chemo-catalysis and a multi-enzymatic in vivo cascade reaction and the development of a highly versatile high-throughput assay for the enzymatic reduction of carboxylic acids. We investigated a biocompatible metal-catalyzed synthesis for the preparation of ? or ? substituted cinnamic acid derivatives which were fed directly into the biocatalytic system. Subsequently, the target molecules were synthesized by an enzymatic cascade consisting of a carboxylate reduction, followed by the selective C-C double bond reduction catalyzed by appropriate enoate reductases. We investigated a biocompatible oxidative Heck protocol and combined it with cells expressing a carboxylic acid reductase from Neurospora crassa (NcCAR) and an ene reductase from Saccharomyces pastorianus for the production fragrance aldehydes. Full article

(This article belongs to the Special Issue Biocatalytic Cascade Reactions (in vivo and in vitro))

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13 pages, 2094 KiB

Open AccessArticle

Optimization of a Catalytic Chemoenzymatic Tandem Reaction for the Synthesis of Natural Stilbenes in Continuous Flow

by Florian Lackner, Katharina Hiebler, Bianca Grabner and Heidrun Gruber-Woelfler

Catalysts 2020, 10(12), 1404; https://doi.org/10.3390/catal10121404 - 1 Dec 2020

Cited by 11 | Viewed by 2767

Abstract

In view of the development of efficient processes for the synthesis of high-value compounds, the combination of bio- and chemocatalysis is highly promising. In addition, implementation of immobilized catalysts into continuous setups allows a straightforward separation of the target compound from the reaction [...] Read more.

In view of the development of efficient processes for the synthesis of high-value compounds, the combination of bio- and chemocatalysis is highly promising. In addition, implementation of immobilized catalysts into continuous setups allows a straightforward separation of the target compound from the reaction mixture and ensures uniform product quality. In this work, we report the optimization of a chemoenzymatic tandem reaction in continuous flow and its extended application for the synthesis of pharmacologically active resveratrol and pterostilbene. The tandem reaction involves enzymatic decarboxylation of coumaric acid employing encapsulated phenolic acid decarboxylase from B. subtilis and a Heck coupling of the obtained vinylphenol with an aryl iodide using heterogeneous Pd-Ce-Sn oxides implemented in a packed bed reactor. By optimization of the reaction conditions for the limiting cross-coupling step, the yield of (E)-4-hydroxystilbene using the fully continuous setup could be more than doubled compared to previous work. Furthermore, the improved chemoenzymatic cascade could also be applied to the synthesis of resveratrol and pterostilbene in a continuous fashion. Leaching of the metal catalyst at high temperatures limited the process in many perspectives. Therefore, the feasibility of a reactor setup with reversed flow was experimentally evaluated and approved. Full article

(This article belongs to the Special Issue Continuous-Flow Catalysis)

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19 pages, 4906 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Recent Advances in Enzymatic and Chemoenzymatic Cascade Processes

by Noelia Losada-Garcia, Zaida Cabrera, Paulina Urrutia, Carla Garcia-Sanz, Alicia Andreu and Jose M. Palomo

Catalysts 2020, 10(11), 1258; https://doi.org/10.3390/catal10111258 - 30 Oct 2020

Cited by 39 | Viewed by 6496

Abstract

Cascade reactions have been described as efficient and universal tools, and are of substantial interest in synthetic organic chemistry. This review article provides an overview of the novel and recent achievements in enzyme cascade processes catalyzed by multi-enzymatic or chemoenzymatic systems. The examples [...] Read more.

Cascade reactions have been described as efficient and universal tools, and are of substantial interest in synthetic organic chemistry. This review article provides an overview of the novel and recent achievements in enzyme cascade processes catalyzed by multi-enzymatic or chemoenzymatic systems. The examples here selected collect the advances related to the application of the sequential use of enzymes in natural or genetically modified combination; second, the important combination of enzymes and metal complex systems, and finally we described the application of biocatalytic biohybrid systems on in situ catalytic solid-phase as a novel strategy. Examples of efficient and interesting enzymatic catalytic cascade processes in organic chemistry, in the production of important industrial products, such as the designing of novel biosensors or bio-chemocatalytic systems for medicinal chemistry application, are discussed Full article

(This article belongs to the Special Issue Enzymes in Sustainable Chemistry)

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42 pages, 13978 KiB

Open AccessReview

Artificial Metalloenzymes: From Selective Chemical Transformations to Biochemical Applications

by Tomoki Himiyama and Yasunori Okamoto

Molecules 2020, 25(13), 2989; https://doi.org/10.3390/molecules25132989 - 30 Jun 2020

Cited by 14 | Viewed by 6851

Abstract

Artificial metalloenzymes (ArMs) comprise a synthetic metal complex in a protein scaffold. ArMs display performances combining those of both homogeneous catalysts and biocatalysts. Specifically, ArMs selectively catalyze non-natural reactions and reactions inspired by nature in water under mild conditions. In the past few [...] Read more.

Artificial metalloenzymes (ArMs) comprise a synthetic metal complex in a protein scaffold. ArMs display performances combining those of both homogeneous catalysts and biocatalysts. Specifically, ArMs selectively catalyze non-natural reactions and reactions inspired by nature in water under mild conditions. In the past few years, the construction of ArMs that possess a genetically incorporated unnatural amino acid and the directed evolution of ArMs have become of great interest in the field. Additionally, biochemical applications of ArMs have steadily increased, owing to the fact that compartmentalization within a protein scaffold allows the synthetic metal complex to remain functional in a sea of inactivating biomolecules. In this review, we present updates on: (1) the newly reported ArMs, according to their type of reaction, and (2) the unique biochemical applications of ArMs, including chemoenzymatic cascades and intracellular/in vivo catalysis. We believe that ArMs have great potential as catalysts for organic synthesis and as chemical biology tools for pharmaceutical applications. Full article

(This article belongs to the Special Issue Hybrid Catalysts for Asymmetric Catalysis)

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36 pages, 6771 KiB

Open AccessReview

Leloir Glycosyltransferases in Applied Biocatalysis: A Multidisciplinary Approach

by Luuk Mestrom, Marta Przypis, Daria Kowalczykiewicz, André Pollender, Antje Kumpf, Stefan R. Marsden, Isabel Bento, Andrzej B. Jarzębski, Katarzyna Szymańska, Arkadiusz Chruściel, Dirk Tischler, Rob Schoevaart, Ulf Hanefeld and Peter-Leon Hagedoorn

Int. J. Mol. Sci. 2019, 20(21), 5263; https://doi.org/10.3390/ijms20215263 - 23 Oct 2019

Cited by 74 | Viewed by 9700

Abstract

Enzymes are nature’s catalyst of choice for the highly selective and efficient coupling of carbohydrates. Enzymatic sugar coupling is a competitive technology for industrial glycosylation reactions, since chemical synthetic routes require extensive use of laborious protection group manipulations and often lack regio- and [...] Read more.

Enzymes are nature’s catalyst of choice for the highly selective and efficient coupling of carbohydrates. Enzymatic sugar coupling is a competitive technology for industrial glycosylation reactions, since chemical synthetic routes require extensive use of laborious protection group manipulations and often lack regio- and stereoselectivity. The application of Leloir glycosyltransferases has received considerable attention in recent years and offers excellent control over the reactivity and selectivity of glycosylation reactions with unprotected carbohydrates, paving the way for previously inaccessible synthetic routes. The development of nucleotide recycling cascades has allowed for the efficient production and reuse of nucleotide sugar donors in robust one-pot multi-enzyme glycosylation cascades. In this way, large glycans and glycoconjugates with complex stereochemistry can be constructed. With recent advances, LeLoir glycosyltransferases are close to being applied industrially in multi-enzyme, programmable cascade glycosylations. Full article

(This article belongs to the Special Issue Carbohydrate-Active Enzymes: Structure, Activity and Reaction Products)

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17 pages, 2304 KiB

Open AccessArticle

Multi-Catalytic Route for the Synthesis of (S)-Tembamide

by Laura Leemans, Marc D. Walter, Frank Hollmann, Anett Schallmey and Luuk M. van Langen

Catalysts 2019, 9(10), 822; https://doi.org/10.3390/catal9100822 - 29 Sep 2019

Cited by 3 | Viewed by 4127

Abstract

Enantiopure β-amino alcohols constitute one of the most significant building blocks for the synthesis of active pharmaceutical ingredients. Despite the availability of a range of chiral β-amino alcohols from a chiral pool, there is a growing demand for new enantioselective synthetic routes to [...] Read more.

Enantiopure β-amino alcohols constitute one of the most significant building blocks for the synthesis of active pharmaceutical ingredients. Despite the availability of a range of chiral β-amino alcohols from a chiral pool, there is a growing demand for new enantioselective synthetic routes to vicinal amino alcohols and their derivatives. In the present study, an asymmetric 2-step catalytic route that converts 4-anisaldehyde into a β-amino alcohol derivative, (S)-tembamide, with excellent enantiopurity (98% enantiomeric excess) has been developed. The recently published initial step consists in a concurrent biocatalytic cascade for the synthesis of (S)-4-methoxymandelonitrile benzoate. The O-benzoyl cyanohydrin is then converted to (S)-tembamide in a hydrogenation reaction catalyzed by Raney Ni. To achieve hydrogenation of the nitrile moiety with highest chemoselectivity and enantioretention, various parameters such as nature of the catalyst, reaction temperature and hydrogen pressure were studied. The reported strategy might be transferrable to the synthesis of other N-acyl-β-amino alcohols. Full article

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11 pages, 884 KiB

Open AccessArticle

Developing Multicompartment Biopolymer Hydrogel Beads for Tandem Chemoenzymatic One-Pot Process

by Jan Pauly, Harald Gröger and Anant V. Patel

Catalysts 2019, 9(6), 547; https://doi.org/10.3390/catal9060547 - 18 Jun 2019

Cited by 12 | Viewed by 5152

Abstract

Chemoenzymatic processes have been gaining interest to implement sustainable reaction steps or even create new synthetic routes. In this study, we combined Grubbs’ second-generation catalyst with pig liver esterase and conducted a chemoenzymatic one-pot process in a tandem mode. To address sustainability, we [...] Read more.

Chemoenzymatic processes have been gaining interest to implement sustainable reaction steps or even create new synthetic routes. In this study, we combined Grubbs’ second-generation catalyst with pig liver esterase and conducted a chemoenzymatic one-pot process in a tandem mode. To address sustainability, we encapsulated the catalysts in biopolymer hydrogel beads and conducted the reaction cascade in an aqueous medium. Unfortunately, conducting the process in tandem led to increased side product formation. We then created core-shell beads with catalysts located in different compartments, which notably enhanced the selectivity towards the desired product compared to homogeneously distributing both catalysts within the matrix. Finally, we designed a specific large-sized bead with a diameter of 13.5 mm to increase the diffusion route of the Grubbs’ catalyst-containing shell. This design forced the ring-closing metathesis to occur first before the substrate could diffuse into the pig liver esterase-containing core, thus enhancing the selectivity to 75%. This study contributes to addressing reaction-related issues by designing specific immobilisates for chemoenzymatic processes. Full article

(This article belongs to the Special Issue Combined Catalytic Systems for Organic Synthesis via Cascade and One-Pot Reactions)

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13 pages, 2841 KiB

Open AccessArticle

Self-Immobilizing Biocatalysts Maximize Space–Time Yields in Flow Reactors

by Theo Peschke, Patrick Bitterwolf, Silla Hansen, Jannis Gasmi, Kersten S. Rabe and Christof M. Niemeyer

Catalysts 2019, 9(2), 164; https://doi.org/10.3390/catal9020164 - 8 Feb 2019

Cited by 25 | Viewed by 7791

Abstract

Maximizing space–time yields (STY) of biocatalytic flow processes is essential for the establishment of a circular biobased economy. We present a comparative study in which different biocatalytic flow reactor concepts were tested with the same enzyme, the (R)-selective alcohol dehydrogenase from [...] Read more.

Maximizing space–time yields (STY) of biocatalytic flow processes is essential for the establishment of a circular biobased economy. We present a comparative study in which different biocatalytic flow reactor concepts were tested with the same enzyme, the (R)-selective alcohol dehydrogenase from Lactobacillus brevis (LbADH), that was used for stereoselective reduction of 5-nitrononane-2,8-dione. The LbADH contained a genetically encoded streptavidin (STV)-binding peptide to enable self-immobilization on STV-coated surfaces. The purified enzyme was immobilized by physisorption or chemisorption as monolayers on the flow channel walls, on magnetic microbeads in a packed-bed format, or as self-assembled all-enzyme hydrogels. Moreover, a multilayer biofilm with cytosolic-expressed LbADH served as a whole-cell biocatalyst. To enable cross-platform comparison, STY values were determined for the various reactor modules. While mono- and multilayer coatings of the reactor surface led to STY < 10, higher productivity was achieved with packed-bed reactors (STY ≈ 100) and the densely packed hydrogels (STY > 450). The latter modules could be operated for prolonged times (>6 days). Given that our approach should be transferable to other enzymes, we anticipate that compartmentalized microfluidic reaction modules equipped with self-immobilizing biocatalysts would be of great utility for numerous biocatalytic and even chemo-enzymatic cascade reactions under continuous flow conditions. Full article

(This article belongs to the Special Issue Flow Biocatalysis)

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