New Advances in Chemoenzymatic Synthesis

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Biocatalysis".

Deadline for manuscript submissions: closed (15 September 2023) | Viewed by 10721

Special Issue Editors


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Guest Editor
Department of Drug Sciences, University of Pavia, Viale Taramelli 12, I-27100 Pavia, Italy
Interests: chemoenzymatic synthesis; medicinal chemistry; biocatalysis; protein engineering
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Guest Editor
Department of Chemistry, University of Milan, Via Golgi 19, Milan, Italy
Interests: organic chemistry; chemoenzymatic synthesis; natural product chemistry; food chemistry
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Chemoenzymatic strategies for the synthesis of complex molecules have recently enriched the field of organic chemistry.

Currently, various examples of the development of chemoenzymatic processes have been described, which have successfully replaced existing chemical processes thanks to the integrated approach of biocatalysis and traditional chemical synthesis. Biocatalysis has been used for laboratory scale and industrial production in order to obtain synthetic pathways characterized by fewer steps, less waste and efficient global synthesis in terms of yields, regio- and stereoselectivity, process robustness and safety. Under this paradigm, enzyme-catalyzed reactions and the flexibility of chemical derivatization are powerful tools for streamlining access to relevant bioactive molecules.

This Thematic Issue covers all aspects of the current applications of chemoenzymatic routes in the synthesis of organic compounds (pharmaceuticals, fine chemicals, food additives, flavors, fragrances) at both the laboratory and industrial scales.

Dr. Teodora Bavaro
Prof. Dr. Giovanna Speranza
Guest Editors

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Keywords

  • chemoenzymatic processes
  • biocatalysis
  • organic synthesis
  • biologically active compounds

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Related Special Issue

Published Papers (5 papers)

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Research

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17 pages, 1600 KiB  
Article
β-Mannosidase from Cellulomonas fimi: Immobilization Study and Application in the β-Mannoside Synthesis
by Marina S. Robescu, Sara Tengattini, Marco Rabuffetti, Giovanna Speranza, Marco Terreni and Teodora Bavaro
Catalysts 2023, 13(11), 1399; https://doi.org/10.3390/catal13111399 - 26 Oct 2023
Viewed by 1174
Abstract
The β-d-mannopyranoside linkage is found in a number of biological structures, in particular, in the core trisaccharide of N-linked glycoproteins, as well as within the antigenic polysaccharides of Salmonella, yeasts, and glycolipids. The construction of this glycosydic bond by [...] Read more.
The β-d-mannopyranoside linkage is found in a number of biological structures, in particular, in the core trisaccharide of N-linked glycoproteins, as well as within the antigenic polysaccharides of Salmonella, yeasts, and glycolipids. The construction of this glycosydic bond by chemical approach is very challenging and requires cumbersome protection and activation steps prior to glycosylation. In this context, β-mannosidase from Cellulomonas fimi (Cf-β-Man) was immobilized for the first time, and it was employed in the synthesis of β-mannosides. Cf-β-Man immobilized on IDA-Co2+-agarose allows the synthesis of the disaccharide, cyanomethyl β-d-mannopyranosyl-(1→6)-2-acetamido-2-deoxy-1-thio-β-d-glucopyranoside, with a higher conversion compared to the soluble enzyme (20% vs. 5%) after 6 h under best conditions. This explorative work opens new scenarios concerning the design of engineered Cf-β-Man mutants and their immobilization in order to obtain a robust and recyclable biocatalyst for applications in chemoenzymatic glycan synthesis. Full article
(This article belongs to the Special Issue New Advances in Chemoenzymatic Synthesis)
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20 pages, 2433 KiB  
Article
Flexibility and Function of Distal Substrate-Binding Tryptophans in the Blue Mussel β-Mannanase MeMan5A and Their Role in Hydrolysis and Transglycosylation
by Simon Birgersson, Johan Morrill, Olof Stenström, Mathias Wiemann, Ulrich Weininger, Pär Söderhjelm, Mikael Akke and Henrik Stålbrand
Catalysts 2023, 13(9), 1281; https://doi.org/10.3390/catal13091281 - 7 Sep 2023
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Abstract
β-Mannanases hydrolyze β-mannans, important components of plant and microalgae cell walls. Retaining β-mannanases can also catalyze transglycosylation, forming new β-mannosidic bonds that are applicable for synthesis. This study focused on the blue mussel (Mytilus edulis) GH5_10 β-mannanase MeMan5A, which contains [...] Read more.
β-Mannanases hydrolyze β-mannans, important components of plant and microalgae cell walls. Retaining β-mannanases can also catalyze transglycosylation, forming new β-mannosidic bonds that are applicable for synthesis. This study focused on the blue mussel (Mytilus edulis) GH5_10 β-mannanase MeMan5A, which contains two semi-conserved tryptophans (W240 and W281) in the distal subsite +2 of its active site cleft. Variants of MeMan5A were generated by replacing one or both tryptophans with alanines. The substitutions reduced the enzyme’s catalytic efficiency (kcat/Km using galactomannan) by three-fold (W281A), five-fold (W240A), or 20-fold (W240A/W281A). Productive binding modes were analyzed by 18O labeling of hydrolysis products and mass spectrometry. Results show that the substitution of both tryptophans was required to shift away from the dominant binding mode of mannopentaose (spanning subsites −3 to +2), suggesting that both tryptophans contribute to glycan binding. NMR spectroscopy and molecular dynamics simulations were conducted to analyze protein flexibility and glycan binding. We suggest that W240 is rigid and contributes to +2 subsite mannosyl specificity, while W281 is flexible, which enables stacking interactions in the +2 subsite by loop movement to facilitate binding. The substitutions significantly reduced or eliminated transglycosylation with saccharides as glycosyl acceptors but had no significant effect on reactions with alcohols. Full article
(This article belongs to the Special Issue New Advances in Chemoenzymatic Synthesis)
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17 pages, 2217 KiB  
Article
Design of a New Chemoenzymatic Process for Producing Epoxidized Monoalkyl Esters from Used Soybean Cooking Oil and Fusel Oil
by Fernanda R. Mattos, José Miguel Júnior, Guilherme J. Sabi, Pedro H. D. Garcia, Patrícia O. Carvalho, Jaine H. H. Luiz and Adriano A. Mendes
Catalysts 2023, 13(3), 543; https://doi.org/10.3390/catal13030543 - 8 Mar 2023
Cited by 1 | Viewed by 2080
Abstract
The aim of this study was to produce epoxidized monoalkyl esters (EMAE), a valuable class of oleochemicals used in a wide range of products and industries, from used soybean cooking oil (USCO) and fusel oil via a three-step chemoenzymatic process. This process consists [...] Read more.
The aim of this study was to produce epoxidized monoalkyl esters (EMAE), a valuable class of oleochemicals used in a wide range of products and industries, from used soybean cooking oil (USCO) and fusel oil via a three-step chemoenzymatic process. This process consists of a first enzymatic hydrolysis of USCO to produce free fatty acids (FFA). Here, five microbial lipases with different specificities were tested as biocatalysts. Full hydrolysis of USCO was obtained after a 180 min reaction time under vigorous stirring (1500 rpm) using a non-specific lipase from Candida rugosa (CRL). Then, monoalkyl esters (MAE) were produced via the esterification of FFA and fusel oil in a solvent-free system using the lipase Eversa® Transform 2.0 (ET2.0) immobilized via physical adsorption on poly(styrenene-divinylbenzene) (PSty-DVB) beads as a biocatalyst. Different water removal strategies (closed and open reactors in the presence or absence of molecular sieves at 5% m.m−1) on the reaction were evaluated. Maximum FFA conversions of 64.3 ± 2.3% (open reactor after a 30 min reaction time) and 73.5 ± 0.4% (closed reactor after a 45 min reaction time) were observed at 40 °C, using a stoichiometric FFA:fusel oil molar ratio (1:1), without molecular sieves, and 5 mg of immobilized protein per gram of reaction mixture. Under these conditions, maximum FFA conversion was only 30.2 ± 2.7% after a 210 min reaction time in a closed reactor using soluble lipase. Reusability tests showed better retention of the original activity of immobilized ET2.0 (around 82%) after eight successive batches of esterification reactions conducted in an open reactor. Finally, the produced MAE was epoxidized via the Prilezhaev reaction, a classical chemical epoxidation process, using hydrogen peroxide and formic acid as a homogeneous catalyst. The products were characterized by standard methods and identified using proton nuclear magnetic resonance (1H NMR). Maximum unsaturated bond conversions into epoxy groups were at approximately 33%, with the experimental epoxy oxygen content (OOCexp.) at 1.75–1.78%, and selectivity (S) at 0.81, using both MAEs produced (open or closed reactors). These results show that this new process is a promising approach for value-added oleochemical production from low-cost and renewable raw materials. Full article
(This article belongs to the Special Issue New Advances in Chemoenzymatic Synthesis)
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Review

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22 pages, 2423 KiB  
Review
Applications of Brewer’s Spent Grain Hemicelluloses in Biorefineries: Extraction and Value-Added Product Obtention
by Aline Ruth Schmidt, Aline Perin Dresch, Sergio Luiz Alves Junior, João Paulo Bender and Helen Treichel
Catalysts 2023, 13(4), 755; https://doi.org/10.3390/catal13040755 - 15 Apr 2023
Cited by 5 | Viewed by 2033
Abstract
A circular economy is imperative for environmental sustainability. In this context, biorefineries stand out as a means of production able to reduce the carbon footprint and the impact of global warming. Biorefineries may employ lignocellulosic biomass from various plant sources to produce bioproducts [...] Read more.
A circular economy is imperative for environmental sustainability. In this context, biorefineries stand out as a means of production able to reduce the carbon footprint and the impact of global warming. Biorefineries may employ lignocellulosic biomass from various plant sources to produce bioproducts with the potential to replace fossil derivatives through synthesis by microorganisms without competing with food crops. Brewer’s spent grain (BSG), the residue of the brewery production process, is an option with potential for use, being a cheap raw material highly available throughout the year. The chemical composition of this biomass is quite variable, with significant amounts of hemicellulose, mainly consisting of xylose and arabinose monomers that can be technologically converted into value-added products such as xylooligosaccharides, xylitol, second-generation ethanol (2G ethanol), biofilms and furfural. To this end, catalysts are unusual in making biorefineries increasingly competitive in the market, selectively optimizing reactions and reducing the environmental impact of the production processes of these bioproducts. The present review addresses the primary methods for extracting and processing hemicelluloses from BSG using either biocatalysts (enzymes) or homogenous (acids, alkali, and salts) and heterogenous catalysts (solid acids and metal oxide) that can be used to pretreat the biomass and obtain the preferred byproducts. The state of the art of optimized catalysis mechanisms is also presented. Full article
(This article belongs to the Special Issue New Advances in Chemoenzymatic Synthesis)
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26 pages, 3915 KiB  
Review
A Review on the Progress in Chemo-Enzymatic Processes for CO2 Conversion and Upcycling
by Kalaimani Markandan, Revathy Sankaran, Yong Wei Tiong, Humaira Siddiqui, Mohammad Khalid, Sumira Malik and Sarvesh Rustagi
Catalysts 2023, 13(3), 611; https://doi.org/10.3390/catal13030611 - 17 Mar 2023
Cited by 4 | Viewed by 2927
Abstract
The increasing concentration of atmospheric CO2 due to human activities has resulted in serious environmental issues such as global warming and calls for efficient ways to reduce CO2 from the environment. The conversion of CO2 into value-added compounds such as [...] Read more.
The increasing concentration of atmospheric CO2 due to human activities has resulted in serious environmental issues such as global warming and calls for efficient ways to reduce CO2 from the environment. The conversion of CO2 into value-added compounds such as methane, formic acid, and methanol has emerged as a promising strategy for CO2 utilization. Among the different techniques, the enzymatic approach based on the CO2 metabolic process in cells presents a powerful and eco-friendly method for effective CO2 conversion and upcycling. This review discusses the catalytic conversion of CO2 using single and multienzyme systems, followed by various chemo-enzymatic processes to produce bicarbonates, bulk chemicals, synthetic organic fuel and synthetic polymer. We also highlight the challenges and prospects for future progress in CO2 conversion via chemo-enzymatic processes for a sustainable solution to reduce the global carbon footprint. Full article
(This article belongs to the Special Issue New Advances in Chemoenzymatic Synthesis)
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