Special Issue "Multi-Step Syntheses in Biology & Chemistry"

A special issue of Catalysts (ISSN 2073-4344).

Deadline for manuscript submissions: closed (31 August 2020).

Special Issue Editor

Prof. Dr. Harald Gröger
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Guest Editor
Chair of Industrial Organic Chemistry and Biotechnology, Faculty of Chemistry, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany
Interests: enzymatic processes; biocatalytic syntheses with whole cell-catalysts; reaction medium engineering in biocatalysis; technical biocatalytic processes; green chemistry–sustainable syntheses; industrial production processes
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Special Issue Information

Dear Colleagues,

Bio- and chemocatalysis are among today’s key technologies that will shape not only the industrial landscape but also our daily lives in the future. This interdisciplinary field of research, which combines biology and chemistry, opens great perspectives for basic research as well as for industrial applications. A particular opportunity and, at the same time, a challenge is to combine various synthetic steps catalyzed by enzymes and/or man-made catalysts towards multi-step syntheses. Such synthetic cascades can enable novel pathways to obtain the molecules required by various components of the industrial product tree, e.g., pharmaceuticals. The combination of individual steps for a compound synthesis can proceed in a sequential fashion with intermediate isolation of the product of interest or by merging these reactions within a one-pot cascade. Such processes consisting of multiple steps might be based only on the use of enzymes or chemocatalysts or can be realized by integrating both “worlds of catalysts” within a synthetic pathway. Addressing these fascinating research areas, this Special Issue will focus on the fields of tailor-made bio-catalyst design and applications thereof, combination of biocatalysis and chemocatalysis, and synthetic biology towards multi-step syntheses from both an academic and an industrial perspective. In addition, recent trends, so far mostly emerging from the area of chemocatalysis but expected to have a strong impact on biocatalysis in the future, will be addressed such as, for example, flow chemistry and machine learning self-automatization. Although this Special Issue is being organized on the occasion of the 13th International CeBiTec Symposium “Multi-Step Syntheses in Biology & Chemistry—An International Young Investigator Conference” that will be held at Bielefeld University on December 2–4, 2019, the invitation to submit manuscripts is open to all colleagues active in this research field. Thus, submission of manuscripts from researchers reporting their latest results on these above-mentioned topics are very much welcome.

Prof. Dr. Harald Gröger
Guest Editor

Manuscript Submission Information

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Keywords

  • Biocatalysis
  • cascades
  • chemocatalysis
  • enzyme catalysis
  • fine chemicals
  • flow chemistry
  • industrial synthesis
  • multi-step synthesis
  • natural products
  • one-pot processes
  • pharmaceutical intermediates
  • pharmaceuticals
  • self-automatization

Published Papers (6 papers)

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Research

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Open AccessFeature PaperArticle
Immobilization of Aldoxime Dehydratases and Their Use as Biocatalysts in Aqueous Reaction Media
Catalysts 2020, 10(9), 1073; https://doi.org/10.3390/catal10091073 - 17 Sep 2020
Abstract
Immobilization of biocatalysts is a current topic in research enabling the easy recovery of catalysts from the reaction medium after the reaction, and it is often accompanied by a stabilization of the catalysts, which enables recycling. Within our ongoing research on the utilization [...] Read more.
Immobilization of biocatalysts is a current topic in research enabling the easy recovery of catalysts from the reaction medium after the reaction, and it is often accompanied by a stabilization of the catalysts, which enables recycling. Within our ongoing research on the utilization of aldoxime dehydratases in the cyanide-free synthesis of nitriles through dehydration of readily available aldoximes, a screening of different immobilization methods for free enzymes was performed. The applied immobilization methods are based on covalent binding and hydrophobic interactions of the enzyme with the carrier material and whole-cell immobilization in calcium alginate beads with and without subsequent coating. In our study, we found that the immobilization with purified free aldoxime dehydratases from OxdRE (Rhodococcus erythropolis) and OxdB (Bacillus sp. strain OxB-1) leads to high immobilization efficiencies, but also to a strong loss of activity with a residual activity of <20%, regardless of the carrier material used. However, when using whole cells for immobilization instead of purified enzymes, we could increase the residual activity significantly. Escherichia coli BL21(DE3)-CodonPlus-RIL OxdRE and OxdB whole cells were entrapped in calcium alginate beads and coated with silica using tetraethylorthosilicate (TEOS), leading to immobilized catalysts with up to 75% residual activity and a higher stability compared to the free whole cells. Even after three rounds of recycling, which corresponds to a 3 d reaction time, the immobilized OxdB whole cells showed a residual activity of 85%. Full article
(This article belongs to the Special Issue Multi-Step Syntheses in Biology & Chemistry)
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Open AccessArticle
Flux Enforcement for Fermentative Production of 5-Aminovalerate and Glutarate by Corynebacterium glutamicum
Catalysts 2020, 10(9), 1065; https://doi.org/10.3390/catal10091065 - 16 Sep 2020
Abstract
Bio-based plastics represent an increasing percentage of the plastics economy. The fermentative production of bioplastic monomer 5-aminovalerate (5AVA), which can be converted to polyamide 5 (PA 5), has been established in Corynebacterium glutamicum via two metabolic pathways. l-lysine can be converted to [...] Read more.
Bio-based plastics represent an increasing percentage of the plastics economy. The fermentative production of bioplastic monomer 5-aminovalerate (5AVA), which can be converted to polyamide 5 (PA 5), has been established in Corynebacterium glutamicum via two metabolic pathways. l-lysine can be converted to 5AVA by either oxidative decarboxylation and subsequent oxidative deamination or by decarboxylation to cadaverine followed by transamination and oxidation. Here, a new three-step pathway was established by using the monooxygenase putrescine oxidase (Puo), which catalyzes the oxidative deamination of cadaverine, instead of cadaverine transaminase. When the conversion of 5AVA to glutarate was eliminated and oxygen supply improved, a 5AVA titer of 3.7 ± 0.4 g/L was reached in microcultivation that was lower than when cadaverine transaminase was used. The elongation of the new pathway by 5AVA transamination by GABA/5AVA aminotransferase (GabT) and oxidation by succinate/glutarate semialdehyde dehydrogenase (GabD) allowed for glutarate production. Flux enforcement by the disruption of the l-glutamic acid dehydrogenase-encoding gene gdh rendered a single transaminase (GabT) in glutarate production via the new pathway responsible for nitrogen assimilation, which increased the glutarate titer to 7.7 ± 0.7 g/L, i.e., 40% higher than with two transaminases operating in glutarate biosynthesis. Flux enforcement was more effective with one coupling site, thus highlighting requirements regarding the modularity and stoichiometry of pathway-specific flux enforcement for microbial production. Full article
(This article belongs to the Special Issue Multi-Step Syntheses in Biology & Chemistry)
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Open AccessFeature PaperArticle
Enhancement of S-Adenosylmethionine-Dependent Methylation by Integrating Methanol Metabolism with 5-Methyl-Tetrahydrofolate Formation in Escherichia coli
Catalysts 2020, 10(9), 1001; https://doi.org/10.3390/catal10091001 - 02 Sep 2020
Abstract
S-Adenosylmethionine (SAM)-dependent methyltransferases are important tools for the biocatalytic methylation of diverse biomolecules. Methylation by a whole-cell biocatalyst allows the utilization of intrinsic SAM and its regeneration system, which consists of a cyclic and multi-step enzymatic cascade. However, low intracellular availability of [...] Read more.
S-Adenosylmethionine (SAM)-dependent methyltransferases are important tools for the biocatalytic methylation of diverse biomolecules. Methylation by a whole-cell biocatalyst allows the utilization of intrinsic SAM and its regeneration system, which consists of a cyclic and multi-step enzymatic cascade. However, low intracellular availability of 5-methyl-tetrahydrofolate (5-methyl-THF), which functions as a methyl group donor, limits SAM regeneration. Here, we integrated methanol metabolism with 5-methyl-THF formation into SAM-dependent methylation system in Escherichia coli, driven by heterologously expressed methanol dehydrogenase (MDH). The coupling of MDH-catalyzed methanol oxidation with the E. coli endogenous reactions enhances the formation of 5-methyl-THF using methanol as a source of methyl group, thereby promoting both the SAM regeneration and methylation reactions. Co-expression of the mutant MDH2 from Cupriavidus necator N-1 with the O-methyltransferase 5 from Streptomyces avermitilis MA-4680 enhanced O-methylation of esculetin 1.4-fold. Additional overexpression of the E. coli endogenous 5,10-methylene-THF reductase, which catalyzes the last step of 5-methyl-THF formation, further enhanced the methylation reaction by 1.9-fold. Together with deregulation of SAM biosynthesis, the titer of methylated compounds was increased about 20-fold (from 0.023 mM to 0.44 mM). The engineered E. coli strain with enhanced 5-methyl-THF formation is now available as a chassis strain for the production of a variety of methylated compounds. Full article
(This article belongs to the Special Issue Multi-Step Syntheses in Biology & Chemistry)
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Open AccessCommunication
Vanadium(V) Complex-Catalyzed One-Pot Synthesis of Phenanthridines via a Pictet-Spengler-Dehydrogenative Aromatization Sequence
Catalysts 2020, 10(8), 860; https://doi.org/10.3390/catal10080860 - 02 Aug 2020
Abstract
Phenanthridine and its derivatives are important structural motifs that exist in natural products, biologically active compounds, and functional materials. Here, we report a mild, one-pot synthesis of 6-arylphenanthridine derivatives by a sequential cascade Pictet-Spengler-dehydrogenative aromatization reaction mediated by oxovanadium(V) complexes under aerobic conditions. [...] Read more.
Phenanthridine and its derivatives are important structural motifs that exist in natural products, biologically active compounds, and functional materials. Here, we report a mild, one-pot synthesis of 6-arylphenanthridine derivatives by a sequential cascade Pictet-Spengler-dehydrogenative aromatization reaction mediated by oxovanadium(V) complexes under aerobic conditions. The reaction of 2-(3,5-dimethoxyphenyl)aniline with a range of commercially available aryl aldehydes provided the desired phenanthridine derivatives in up to 96% yield. The ability of vanadium(V) complexes to function as efficient redox and Lewis acid catalysts enables the sequential reaction to occur under mild conditions. Full article
(This article belongs to the Special Issue Multi-Step Syntheses in Biology & Chemistry)
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Open AccessFeature PaperArticle
Aldoxime Dehydratase Mutants as Improved Biocatalysts for a Sustainable Synthesis of Biorenewables-Based 2-Furonitrile
Catalysts 2020, 10(4), 362; https://doi.org/10.3390/catal10040362 - 26 Mar 2020
Abstract
2-Furonitrile is an interesting nitrile product for the chemical industry due to its use as intermediate in the field of fine chemicals and pharmaceuticals or as a potential sweetener, as well as due to its access from biorenewables. As an alternative to current [...] Read more.
2-Furonitrile is an interesting nitrile product for the chemical industry due to its use as intermediate in the field of fine chemicals and pharmaceuticals or as a potential sweetener, as well as due to its access from biorenewables. As an alternative to current processes based on, e.g., the ammoxidation of furfural with ammonia as a gas phase reaction running at > 400 °C, we recently reported an enzymatic dehydration of 2-furfuryl aldoxime being obtained easily from furfural and hydroxylamine. However, improving the catalytic properties of the aldoxime dehydratase biocatalyst from Rhodococcus sp. YH3-3 (OxdYH3-3) in terms of activity and stability remained a challenge. In this contribution, the successful development of aldoxime dehydratase OxdYH3-3 mutants that were generated by directed evolution and its enhanced activity toward 2-furfuryl aldoxime is reported. The mutant OxdYH3-3 N266S showed an improved activity of up to six times higher than the wild type when utilizing a substrate concentration of 50–100 mM of 2-furfuryl aldoxime. Full article
(This article belongs to the Special Issue Multi-Step Syntheses in Biology & Chemistry)
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Review

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Open AccessReview
Fatty Acid Hydratases: Versatile Catalysts to Access Hydroxy Fatty Acids in Efficient Syntheses of Industrial Interest
Catalysts 2020, 10(3), 287; https://doi.org/10.3390/catal10030287 - 03 Mar 2020
Abstract
The utilization of hydroxy fatty acids has gained more and more attention due to its applicability in many industrial building blocks that require it, for example, polymers or fragrances. Furthermore, hydroxy fatty acids are accessible from biorenewables, thus contributing to a more sustainable [...] Read more.
The utilization of hydroxy fatty acids has gained more and more attention due to its applicability in many industrial building blocks that require it, for example, polymers or fragrances. Furthermore, hydroxy fatty acids are accessible from biorenewables, thus contributing to a more sustainable raw material basis for industrial chemicals. Therefore, a range of investigations were done on fatty acid hydratases (FAHs), since these enzymes catalyze the addition of water to an unsaturated fatty acid, thus providing an elegant route towards hydroxy-substituted fatty acids. Besides the discovery and characterization of fatty acid hydratases (FAHs), the design and optimization of syntheses with these enzymes, the implementation in elaborate cascades, and the improvement of these biocatalysts, by way of mutation in terms of the substrate scope, has been investigated. This mini-review focuses on the research done on process development using fatty acid hydratases as a catalyst. It is notable that biotransformations, running at impressive substrate loadings of up to 280 g L−1, have been realized. A further topic of this mini-review is the implementation of fatty acid hydratases in cascade reactions. In such cascades, fatty acid hydratases were, in particular, combined with alcohol dehydrogenases (ADH), Baeyer-Villiger monooxygenases (BVMO), transaminases (TA) and hydrolases, thus enabling access to a broad variety of molecules that are of industrial interest. Full article
(This article belongs to the Special Issue Multi-Step Syntheses in Biology & Chemistry)
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