Articoli di riviste: "Whole-Cell biotransformations"

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Wackett, Lawrence P. "Biocatalysis and whole cell biotransformations". Microbial Biotechnology 2, n. 6 (20 ottobre 2009): 642–43. http://dx.doi.org/10.1111/j.1751-7915.2009.00156.x.

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Allen, C. C. R., C. J. Boudet, C. Hardacre e M. E. Migaud. "Enhancement of whole cell dioxygenase biotransformations of haloarenes by toxic ionic liquids". RSC Adv. 4, n. 38 (2014): 19916–24. http://dx.doi.org/10.1039/c4ra00640b.

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Salter, Gary J., e Douglas B. Kelt. "Solvent Selection for Whole Cell Biotransformations in Organic Media". Critical Reviews in Biotechnology 15, n. 2 (gennaio 1995): 139–77. http://dx.doi.org/10.3109/07388559509147404.

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Seo, Hyo-Seel, Na-Rae Lee, Eun-Hee Doo, Sunghoon Park e Jin-Byung Park. "Development of efficient whole-cell biocatalysts for oxidative biotransformations". Journal of Bioscience and Bioengineering 108 (novembre 2009): S43. http://dx.doi.org/10.1016/j.jbiosc.2009.08.124.

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Garikipati, S. V. B. Janardhan, Angela M. McIver e Tonya L. Peeples. "Whole-Cell Biocatalysis for 1-Naphthol Production in Liquid-Liquid Biphasic Systems". Applied and Environmental Microbiology 75, n. 20 (21 agosto 2009): 6545–52. http://dx.doi.org/10.1128/aem.00434-09.

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ABSTRACT Whole-cell biocatalysis to oxidize naphthalene to 1-naphthol in liquid-liquid biphasic systems was performed. Escherichia coli expressing TOM-Green, a variant of toluene ortho-monooxygenase (TOM), was used for this oxidation. Three different solvents, dodecane, dioctyl phthalate, and lauryl acetate, were screened for biotransformations in biphasic media. Of the solvents tested, lauryl acetate gave the best results, producing 0.72 ± 0.03 g/liter 1-naphthol with a productivity of 0.46 ± 0.02 g/g (dry weight) cells after 48 h. The effects of the organic phase ratio and the naphthalene concentration in the organic phase were investigated. The highest 1-naphthol concentration (1.43 g/liter) and the highest 1-naphthol productivity (0.55 g/g [dry weight] cells) were achieved by optimization of the organic phase. The ability to recycle both free cells and cells immobilized in calcium alginate was tested. Both free and immobilized cells lost more than ∼60% of their activity after the first run, which could be attributed to product toxicity. On a constant-volume basis, an eightfold improvement in 1-naphthol production was achieved using biphasic media compared to biotransformation in aqueous media.

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Winder, Catherine L., Robert Cornmell, Stephanie Schuler, Roger M. Jarvis, Gill M. Stephens e Royston Goodacre. "Metabolic fingerprinting as a tool to monitor whole-cell biotransformations". Analytical and Bioanalytical Chemistry 399, n. 1 (31 ottobre 2010): 387–401. http://dx.doi.org/10.1007/s00216-010-4342-z.

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Wu, Shuke, e Zhi Li. "Whole-Cell Cascade Biotransformations for One-Pot Multistep Organic Synthesis". ChemCatChem 10, n. 10 (23 febbraio 2018): 2164–78. http://dx.doi.org/10.1002/cctc.201701669.

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Grigoriou, Stylianos, Pierre Kugler, Evelina Kulcinskaja, Frederik Walter, John King, Phil Hill, Volker F. Wendisch e Elaine O'Reilly. "Development of a Corynebacterium glutamicum bio-factory for self-sufficient transaminase reactions". Green Chemistry 22, n. 13 (2020): 4128–32. http://dx.doi.org/10.1039/d0gc01432j.

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The development and application of a self-sufficient whole-cell system for transaminase biotransformations is described. The system relies on an engineered strain of Corynebacterium glutamicum that produces smart amine donors.

9

Biermann, Marc, Daniel Bakonyi, Werner Hummel e Harald Gröger. "Design of recombinant whole-cell catalysts for double reduction of CC and CO bonds in enals and application in the synthesis of Guerbet alcohols as industrial bulk chemicals for lubricants". Green Chemistry 19, n. 2 (2017): 405–10. http://dx.doi.org/10.1039/c6gc01668e.

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Whole-cell catalysts overexpressing two enzymes for a double reduction cascade in which aliphatic α-branched α,β-unsaturated aldehydes are converted into Guerbet alcohols as a highly demanded class of lubricants were constructed and applied in such biotransformations.

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Zia, Muhammad Farooq, Ágnes G. Vasko, Zsuzsanna Riedl, Christian Hametner, György Hajós, Kurt Mereiter e Marko D. Mihovilovic. "Biodihydroxylation of substituted quinolines and isoquinolines by recombinant whole-cell mediated biotransformations". Tetrahedron 72, n. 46 (novembre 2016): 7348–55. http://dx.doi.org/10.1016/j.tet.2016.06.077.

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Sprenger, Georg A., Florian Baumgärtner e Christoph Albermann. "Production of human milk oligosaccharides by enzymatic and whole-cell microbial biotransformations". Journal of Biotechnology 258 (settembre 2017): 79–91. http://dx.doi.org/10.1016/j.jbiotec.2017.07.030.

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Siebert, Nina Antonia, Alexander Franz e Rohan Karande. "Phototrophe Biofilme für die kontinuierliche Produktion von Chemikalien". BIOspektrum 28, n. 2 (marzo 2022): 212–14. http://dx.doi.org/10.1007/s12268-022-1723-8.

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AbstractCyanobacteria are considered to be promising host organisms to perform whole-cell biotransformations and for the sustainable production of value-added compounds. However, for their commercial applications, scalable photobioreactors that allow high cell density cultivation, stable and long-term catalytic performance, and high product formation are necessary. Cyanobacterial biofilms in capillary reactors present a promising alternative to overcome some of these challenges.

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Burton, Stephanie G. "Development of bioreactors for application of biocatalysts in biotransformations and bioremediation". Pure and Applied Chemistry 73, n. 1 (1 gennaio 2001): 77–83. http://dx.doi.org/10.1351/pac200173010077.

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Biotransformation systems, whether used for environmentally benign biocatalysis of synthetic reactions, or bioremediation of pollutants, require suitable biocatalysts and suitable bioreactor systems with particular characteristics. Our research focuses on the bioconversion of organic compounds, many of which are industrial residues, such as phenols, poly-aromatic hydrocarbons, heterocyclic compounds, and polychlorinated biphenyls. The purpose of such biotransformations can be twofold: firstly, to remove them from effluents and convert them to less toxic forms, and secondly, to convert them into products with economic value. We conduct research in utilizing various isolated-enzyme and whole-cell biological agents; bioreactors, including novel membrane bioreactors, are used as a means of supporting/immobilizing, and hence applying, these biocatalysts in continuous systems. In addition, the enzyme systems are characterized biochemically, to provide information which is required in modification, adaptation, and scale-up of the bioreactors. The paper summarizes research on application of biofilms of fungal and bacterial cells and their enzymes, including hydrolases, polyphenol oxidase, peroxidase and laccase, in bioreactor systems including continuously operating membrane bioreactors.

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McCormick, Susan P., Neil P. J. Price e Cletus P. Kurtzman. "Glucosylation and Other Biotransformations of T-2 Toxin by Yeasts of the Trichomonascus Clade". Applied and Environmental Microbiology 78, n. 24 (5 ottobre 2012): 8694–702. http://dx.doi.org/10.1128/aem.02391-12.

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ABSTRACTTrichothecenes are sesquiterpenoid toxins produced byFusariumspecies. Since these mycotoxins are very stable, there is interest in microbial transformations that can remove toxins from contaminated grain or cereal products. Twenty-three yeast species assigned to theTrichomonascusclade (Saccharomycotina, Ascomycota), including fourTrichomonascusspecies and 19 anamorphic species presently classified inBlastobotrys, were tested for their ability to convert the trichothecene T-2 toxin to less-toxic products. These species gave three types of biotransformations: acetylation to 3-acetyl T-2 toxin, glycosylation to T-2 toxin 3-glucoside, and removal of the isovaleryl group to form neosolaniol. Some species gave more than one type of biotransformation. ThreeBlastobotrysspecies converted T-2 toxin into T-2 toxin 3-glucoside, a compound that has been identified as a masked mycotoxin inFusarium-infected grain. This is the first report of a microbial whole-cell method for producing trichothecene glycosides, and the potential large-scale availability of T-2 toxin 3-glucoside will facilitate toxicity testing and development of methods for detection of this compound in agricultural and other products.

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Raczyńska, Agnieszka, Joanna Jadczyk e Małgorzata Brzezińska-Rodak. "Altering the Stereoselectivity of Whole-Cell Biotransformations via the Physicochemical Parameters Impacting the Processes". Catalysts 11, n. 7 (27 giugno 2021): 781. http://dx.doi.org/10.3390/catal11070781.

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The enantioselective synthesis of organic compounds is one of the great challenges in organic synthetic chemistry due to its importance for the acquisition of biologically active derivatives, e.g., pharmaceuticals, agrochemicals, and others. This is why biological systems are increasingly applied as tools for chiral compounds synthesis or modification. The use of whole cells of “wild-type” microorganisms is one possible approach, especially as some methods allow improving the conversion degrees and controlling the stereoselectivity of the reaction without the need to introduce changes at the genetic level. Simple manipulation of the culture conditions, the form of a biocatalyst, or the appropriate composition of the biotransformation medium makes it possible to obtain optically pure products in a cheap, safe, and environmentally friendly manner. This review contains selected examples of the influence of physicochemical factors on the stereochemistry of the biocatalytic preparation of enantiomerically pure compounds, which is undertaken through kinetically controlled separation of their racemic mixtures or reduction of prochiral ketones and has an effect on the final enantiomeric purity and enantioselectivity of the reaction.

16

Nikolova, Penka, e Owen P. Ward. "Whole cell yeast biotransformations in two-phase systems: Effect of solvent on product formation and cell structure". Journal of Industrial Microbiology 10, n. 3-4 (settembre 1992): 169–77. http://dx.doi.org/10.1007/bf01569762.

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Leppchen, Kathrin, Thomas Daussmann, Simon Curvers e Martin Bertau. "Microbial De-emulsification: A Highly Efficient Procedure for the Extractive Workup of Whole-Cell Biotransformations". Organic Process Research & Development 10, n. 6 (novembre 2006): 1119–25. http://dx.doi.org/10.1021/op060113o.

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Majewska, Paulina, Monika Serafin, Magdalena Klimek-Ochab, Małgorzata Brzezińska-Rodak e Ewa Żymańczyk-Duda. "Lipases and whole cell biotransformations of 2-hydroxy-2-(ethoxyphenylphosphinyl)acetic acid and its ester". Bioorganic Chemistry 66 (giugno 2016): 21–26. http://dx.doi.org/10.1016/j.bioorg.2016.02.011.

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Alphand, Véronique, Nicoletta Gaggero, Stefano Colonna, Piero Pasta e Roland Furstoss. "Microbiological transformations 36: Preparative scale synthesis of chiral thioacetal and thioketal sulfoxides using whole-cell biotransformations". Tetrahedron 53, n. 28 (luglio 1997): 9695–706. http://dx.doi.org/10.1016/s0040-4020(97)00647-9.

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Fisk, Heidi, Yun Xu, Chloe Westley, Nicholas J. Turner, Jason Micklefield e Royston Goodacre. "From Multistep Enzyme Monitoring to Whole-Cell Biotransformations: Development of Real-Time Ultraviolet Resonance Raman Spectroscopy". Analytical Chemistry 89, n. 22 (8 novembre 2017): 12527–32. http://dx.doi.org/10.1021/acs.analchem.7b03742.

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Myles, David C., e George M. Whitesides. "Biotransformations in preparative organic chemistry, the use of isolated enzymes and whole cell systems in synthesis". Bioorganic Chemistry 18, n. 2 (giugno 1990): 251. http://dx.doi.org/10.1016/0045-2068(90)90046-8.

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Linares-Pastén, Javier A., Georgina Chávez-Lizárraga, Rodrigo Villagomez, Gashaw Mamo e Rajni Hatti-Kaul. "A method for rapid screening of ketone biotransformations: Detection of whole cell Baeyer–Villiger monooxygenase activity". Enzyme and Microbial Technology 50, n. 2 (febbraio 2012): 101–6. http://dx.doi.org/10.1016/j.enzmictec.2011.10.004.

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Jörg, Gerhard, Kathrin Leppchen, Thomas Daussmann e Martin Bertau. "A novel convenient procedure for extractive work-up of whole-cell biotransformations using de-emulsifying hydrolases". Biotechnology and Bioengineering 87, n. 4 (23 luglio 2004): 525–36. http://dx.doi.org/10.1002/bit.20155.

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Schroer, Kirsten, Bruno Zelic, Marco Oldiges e Stephan Lütz. "Metabolomics for biotransformations: Intracellular redox cofactor analysis and enzyme kinetics offer insight into whole cell processes". Biotechnology and Bioengineering 104, n. 2 (1 ottobre 2009): 251–60. http://dx.doi.org/10.1002/bit.22390.

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Pereira dos Santos, Valmore Henrique, Dorval Moreira Coelho Neto, Valdemar Lacerda Júnior, Warley de Souza Borges e Eliane de Oliveira Silva. "Fungal Biotransformation: An Efficient Approach for Stereoselective Chemical Reactions". Current Organic Chemistry 24, n. 24 (31 dicembre 2020): 2902–53. http://dx.doi.org/10.2174/1385272824999201111203506.

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Abstract:: There is great interest in developing chemical technologies to achieve regioselective and stereoselective reactions since only one enantiomer is required for producing the chiral leads for drug development. These selective reactions are provided by traditional chemical synthetic methods, even under expensive catalysts and long reaction times. Filamentous fungi are efficient biocatalysts capable of catalyzing a wide variety of reactions with significant contributions to the development of clean and selective processes. Although some enzymes have already been employed in isolated forms or as crude protein extracts as catalysts for conducting selective reactions, the use of whole-cell provides advantages regarding cofactor regenerations. It is also possible to carry out conversions at chemically unreactive positions and to perform racemic resolution through microbial transformation. The current literature contains several reports on the biotransformation of different compounds by fungi, which generated chemical analogs with high selectivity, using mild and eco-friendly conditions. Prompted by the enormous pharmacological interest in the development of stereoselective chemical technologies, this review covers the biotransformations catalyzed by fungi that yielded chiral products with enantiomeric excesses published over the period 2010-2020. This work highlights new approaches for the achievement of a variety of bioactive chiral building blocks, which can be a good starting point for the synthesis of new compounds combining biotransformation and synthetic organic chemistry.

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Böhmer, Stefanie, Christina Marx, Álvaro Gómez-Baraibar, Marc M. Nowaczyk, Dirk Tischler, Anja Hemschemeier e Thomas Happe. "Evolutionary diverse Chlamydomonas reinhardtii Old Yellow Enzymes reveal distinctive catalytic properties and potential for whole-cell biotransformations". Algal Research 50 (settembre 2020): 101970. http://dx.doi.org/10.1016/j.algal.2020.101970.

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Joo, Sung-Yeon, Hee-Wang Yoo, Sharad Sarak, Byung-Gee Kim e Hyungdon Yun. "Enzymatic Synthesis of ω-Hydroxydodecanoic Acid By Employing a Cytochrome P450 from Limnobacter sp. 105 MED". Catalysts 9, n. 1 (8 gennaio 2019): 54. http://dx.doi.org/10.3390/catal9010054.

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ω-Hydroxylated fatty acids are valuable and versatile building blocks for the production of various adhesives, lubricants, cosmetic intermediates, etc. The biosynthesis of ω-hydroxydodecanoic acid from vegetable oils is one of the important green pathways for their chemical-based synthesis. In the present study, the novel monooxygenase CYP153AL.m from Limnobacter sp. 105 MED was used for the whole-cell biotransformations. We constructed three-component system that was comprised of CYP153AL.m, putidaredoxin and putidaredoxin reductase from Pseudomonas putida. This in vivo study demonstrated that CYP153AL.m is a powerful catalyst for the biosynthesis of ω-hydroxydodecanoic acid. Under optimized conditions, the application of a solid-state powdered substrate rather than a substrate dissolved in DMSO significantly enhanced the overall reaction titer of the process. By employing this efficient system, 2 g/L of 12-hydroxydodecanoic acid (12-OHDDA) was produced from 4 g/L of its corresponding fatty acid, which was namely dodecanoic acid. Furthermore, the system was extended to produce 3.28 g/L of 12-OHDDA using 4 g/L of substrate by introducing native redox partners. These results demonstrate the utility of CYP153AL.m-catalyzed biotransformations in the industrial production of 12-OHDDA and other valuable building blocks.

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Kurze, Elisabeth, Victoria Ruß, Nadia Syam, Isabelle Effenberger, Rafal Jonczyk, Jieren Liao, Chuankui Song, Thomas Hoffmann e Wilfried Schwab. "Glucosylation of (±)-Menthol by Uridine-Diphosphate-Sugar Dependent Glucosyltransferases from Plants". Molecules 26, n. 18 (10 settembre 2021): 5511. http://dx.doi.org/10.3390/molecules26185511.

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Menthol is a cyclic monoterpene alcohol of the essential oils of plants of the genus Mentha, which is in demand by various industries due to its diverse sensorial and physiological properties. However, its poor water solubility and its toxic effect limit possible applications. Glycosylation offers a solution as the binding of a sugar residue to small molecules increases their water solubility and stability, renders aroma components odorless and modifies bioactivity. In order to identify plant enzymes that catalyze this reaction, a glycosyltransferase library containing 57 uridine diphosphate sugar-dependent enzymes (UGTs) was screened with (±)-menthol. The identity of the products was confirmed by mass spectrometry and nuclear magnetic resonance spectroscopy. Five enzymes were able to form (±)-menthyl-β-d-glucopyranoside in whole-cell biotransformations: UGT93Y1, UGT93Y2, UGT85K11, UGT72B27 and UGT73B24. In vitro enzyme activity assays revealed highest catalytic activity for UGT93Y1 (7.6 nkat/mg) from Camellia sinensis towards menthol and its isomeric forms. Although UGT93Y2 shares 70% sequence identity with UGT93Y1, it was less efficient. Of the five enzymes, UGT93Y1 stood out because of its high in vivo and in vitro biotransformation rate. The identification of novel menthol glycosyltransferases from the tea plant opens new perspectives for the biotechnological production of menthyl glucoside.

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ALPHAND, V., N. GAGGERO, S. COLONNA, P. PASTA e R. FURSTOSS. "ChemInform Abstract: Microbiological Transformations. Part 36. Preparative Scale Synthesis of Chiral Thioacetal and Thioketal Sulfoxides Using Whole-Cell Biotransformations." ChemInform 28, n. 50 (2 agosto 2010): no. http://dx.doi.org/10.1002/chin.199750046.

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Rolf, Jascha, Philipp Nerke, Annette Britner, Sebastian Krick, Stephan Lütz e Katrin Rosenthal. "From Cell-Free Protein Synthesis to Whole-Cell Biotransformation: Screening and Identification of Novel α-Ketoglutarate-Dependent Dioxygenases for Preparative-Scale Synthesis of Hydroxy-l-Lysine". Catalysts 11, n. 9 (27 agosto 2021): 1038. http://dx.doi.org/10.3390/catal11091038.

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The selective hydroxylation of non-activated C-H bonds is still a challenging reaction in chemistry. Non-heme Fe2+/α-ketoglutarate-dependent dioxygenases are remarkable biocatalysts for the activation of C-H-bonds, catalyzing mainly hydroxylations. The discovery of new Fe2+/α-ketoglutarate-dependent dioxygenases with suitable reactivity for biotechnological applications is therefore highly relevant to expand the limited range of enzymes described so far. In this study, we performed a protein BLAST to identify homologous enzymes to already described lysine dioxygenases (KDOs). Six novel and yet uncharacterized proteins were selected and synthesized by cell-free protein synthesis (CFPS). The subsequent in vitro screening of the selected homologs revealed activity towards the hydroxylation of l-lysine (Lys) into hydroxy-l-lysine (Hyl), which is a versatile chiral building block. With respect to biotechnological application, Escherichia coli whole-cell biocatalysts were developed and characterized in small-scale biotransformations. As the whole-cell biocatalyst expressing the gene coding for the KDO from Photorhabdus luminescens showed the highest specific activity of 8.6 ± 0.6 U gCDW−1, it was selected for the preparative synthesis of Hyl. Multi-gram scale product concentrations were achieved providing a good starting point for further bioprocess development for Hyl production. A systematic approach was established to screen and identify novel Fe2+/α-ketoglutarate-dependent dioxygenases, covering the entire pathway from gene to product, which contributes to accelerating the development of bioprocesses for the production of value-added chemicals.

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Bräutigam, Stefan, Stephanie Bringer-Meyer e Dirk Weuster-Botz. "Asymmetric whole cell biotransformations in biphasic ionic liquid/water-systems by use of recombinant Escherichia coli with intracellular cofactor regeneration". Tetrahedron: Asymmetry 18, n. 16 (agosto 2007): 1883–87. http://dx.doi.org/10.1016/j.tetasy.2007.08.003.

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Kaderbhai, M. A., S. L. Kelly e N. N. Kaderbhai. "Towards engineered topogenesis of cytochrome b5 and P450 for in vivo transformation of xenobiotics". Biochemical Society Transactions 34, n. 6 (25 ottobre 2006): 1231–35. http://dx.doi.org/10.1042/bst0341231.

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Nature is endowed with catalysts capable of an unprecedented diversity of biotransformations, beyond the capabilities of synthetic chemistries. In a biotechnological context, there is a growing and emerging need to tap this catalytic potential. CYP (cytochrome P450) represents a superfamily of enzymes capable of a diverse array of catalytic activities. Distinct members are engaged in biosynthetic reactions within many organisms, while others have a role in the detoxification of foreign compounds. The latter substrates include medicines, pollutants, pesticides, carcinogens, perfumes and herbicides, representing considerable applied importance for pharmacology and toxicology. CYPs show a high degree of stereo- and regio-specificity for their reactions, which have wide industrial applications. Recombinant CYPs are commonly expressed as active recombinant cytosolic forms in Escherichia coli. However, selective permeability of E. coli to many substrates and products can cause problems with product recovery when using whole-cell systems. To overcome these problems, we have been developing approaches to facilitate export of functional recombinant haemoproteins to the inner membrane, periplasm and the outer membrane of E. coli. Here, we describe the progress in relation to cytochrome b5 and CYPs.

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Blank‐Koblenc, T., R. Tor e A. Freeman. "Cosolvent Effects on Gel‐Entrapped Oxidoreductase: The Glucose Oxidase Model". Biotechnology and Applied Biochemistry 10, n. 1 (febbraio 1988): 32–41. http://dx.doi.org/10.1111/j.1470-8744.1988.tb00004.x.

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An intrinsic problem often involved in biotransformations carried out by immobilized cells is the poor solubility of substrate and product in water. Increase in hydrophobic substrate availability to such gel‐entrapped cells may be attained by the replacement of a fraction of the aqueous medium by water‐miscible solvents (cosolvents). The introduction of cosolvents results in increased solubility, but may simultaneously affect enzymic activity and stability. Recently, criteria and guidelines for cosolvent selection on the basis of its effect on intracellular enzyme stability were reported (Freeman, A., and Lilly, M.D. (1987) Appl. Microbiol. Biotechnol. 25, 495–501). In order to understand the impact of the preferable or unsuitable cosolvents on enzyme kinetics and stability, the effects of 1–5 M concentrations of a series of cosolvents (e.g., ethylene glycol, dimethylsulfoxide, N,N‐dimethylformamide, ethanol) on a well‐characterized, highly specific enzyme model (glucose oxidase) were investigated. The presence of 1–5 M of the cosolvents studied imposed 10–50% reduction in Vmax of the enzyme, but Km was only mildly affected (+/‐ 25%). This inhibition was attributed to cosolvent effect on small, reversible, conformational changes in the enzyme native structure. Determination of the rate constant of thermal inactivation (at 55 degrees C) of glucose oxidase, in the presence of cosolvents, was employed for the quantitative evaluation of cosolvent effect on enzyme stability. A clear pattern of cosolvent preference in respect to its denaturing effect was obtained, which was identical to the pattern previously observed in a study of oxidoreductases operating from within a whole cell. In both cases diols (e.g., ethylene glycol) were found to be the preferable group of cosolvents. Our results indicate that a soluble enzyme and an intracellular enzyme operating from a whole cell are affected by cosolvents via the same mechanism.

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Julsing, Mattijs K., Manfred Schrewe, Sjef Cornelissen, Inna Hermann, Andreas Schmid e Bruno Bühler. "Outer Membrane Protein AlkL Boosts Biocatalytic Oxyfunctionalization of Hydrophobic Substrates in Escherichia coli". Applied and Environmental Microbiology 78, n. 16 (8 giugno 2012): 5724–33. http://dx.doi.org/10.1128/aem.00949-12.

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ABSTRACTThe outer membrane of microbial cells forms an effective barrier for hydrophobic compounds, potentially causing an uptake limitation for hydrophobic substrates. Low bioconversion activities (1.9 U gcdw−1) have been observed for the ω-oxyfunctionalization of dodecanoic acid methyl ester by recombinantEscherichia colicontaining the alkane monooxygenase AlkBGT ofPseudomonas putidaGPo1. Using fatty acid methyl ester oxygenation as the model reaction, this study investigated strategies to improve bacterial uptake of hydrophobic substrates. Admixture of surfactants and cosolvents to improve substrate solubilization did not result in increased oxygenation rates. Addition of EDTA increased the initial dodecanoic acid methyl ester oxygenation activity 2.8-fold. The use of recombinantPseudomonas fluorescensCHA0 instead ofE. coliresulted in a similar activity increase. However, substrate mass transfer into cells was still found to be limiting. Remarkably, the coexpression of thealkLgene ofP. putidaGPo1 encoding an outer membrane protein with so-far-unknown function increased the dodecanoic acid methyl ester oxygenation activity of recombinantE. coli28-fold. In a two-liquid-phase bioreactor setup, a 62-fold increase to a maximal activity of 87 U gcdw−1was achieved, enabling the accumulation of high titers of terminally oxyfunctionalized products. Coexpression ofalkLalso increased oxygenation activities toward the natural AlkBGT substrates octane and nonane, showing for the first time clear evidence for a prominent role of AlkL in alkane degradation. This study demonstrates that AlkL is an efficient tool to boost productivities of whole-cell biotransformations involving hydrophobic aliphatic substrates and thus has potential for broad applicability.

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Klatte, Stephanie, Elisabeth Lorenz e Volker F. Wendisch. "Whole cell biotransformation for reductive amination reactions". Bioengineered 5, n. 1 (5 dicembre 2013): 56–62. http://dx.doi.org/10.4161/bioe.27151.

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Dai, Jungui, Runjiang Qu, Jian-hua Zou e Xiaoguang Chen. "Structural diversification of taxanes by whole-cell biotransformation". Tetrahedron 64, n. 35 (agosto 2008): 8102–16. http://dx.doi.org/10.1016/j.tet.2008.06.062.

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Bringer, Stephanie, e Hermann Sahm. "Reductive and oxidative whole cell biotransformation with bacteria". Journal of Biotechnology 131, n. 2 (settembre 2007): S99. http://dx.doi.org/10.1016/j.jbiotec.2007.07.171.

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Roberts, S. M., e N. M. Williamson. "The Use of Enzymes for the Preparation of Biologically Active Natural Products and Analogues in Optically Active Form". Current Organic Chemistry 1, n. 1 (maggio 1997): 1–20. http://dx.doi.org/10.2174/1385272801666220121181731.

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The enantioselective hydrolysis of chiral esters using esterases and lipases gives access to key optically active intermediates en route to prostaglandins, coriolic acid, the anti-HIV agent carbovir and mevinic acid type hypocholestemic agents. The hydrolysis of meso-esters using hydrolases is a very efficient strategy in organic synthesis and has been used to prepare the carbocyclic nucleosides neplanocin and risteromycin. Acylases have been used to prepare (-)-carbovir and both enantiomers of a GABA-mimetic from 2-azabicyclo[2.2.1)hept-5-en-3-one. The employment of nitrilases and nitrile hydratases is gaining in popularity; for example, prochiral 2-benzoyloxypropane-1,3-dinitrile is hydrolysed to (S)-3-benzoyloxy-4-cyanobutanoic acid with exquisite selectivity. Lipases in organic solvents can effect esterification, transesterification and interesterification reactions and this popular methodology has been used to prepare key norcarbocyclic nucleotides and carbocyclic oxetanocin A in single enantiomer form. Yeast catalysed reductions of ketones afford optically active secondary alcohols, typically employed for the synthesis of pheromones, fragrances and chemotactic agents such as leukotriene-84. Instead of a whole-cell system such as yeast, partially purified dehydrogenases can be employed to synthesise (S)-secondary alcohols, for examplan intermediate to the antifungal agent brefeldin-A. Biohydroxylations are important reactions and are being applied to a wide range of substrates. The oxidation of benzene and derivatives to the corresponding cyclohexadiene diols are classic examples and have provided a route to analogues of cyclophellitol. Similarly, mono-oxygenase catalysed Baeyer-Villiger reactions are now well-documented and have furnished intermediates to carbocyclic-AZT, lipoic acid and azadirachtin. Sulfoxides of high optical purity have been prepared by yeast-catalysed oxidation, while enzymes in the transferase and lyase classes have been used to make carbohydrates and amino acids. In conclusion, the science of biotransformations opens up numerous synthetic routes to a wide variety of target molecules that are not easily accessible by other methods of synthetic organic chemistry.

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Maskow, Thomas, Johannes Lerchner, Mirko Peitzsch, Hauke Harms e Gert Wolf. "Chip calorimetry for the monitoring of whole cell biotransformation". Journal of Biotechnology 122, n. 4 (aprile 2006): 431–42. http://dx.doi.org/10.1016/j.jbiotec.2005.10.008.

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40

Scheibenzuber, Sophie, Thomas Hoffmann, Isabelle Effenberger, Wilfried Schwab, Stefan Asam e Michael Rychlik. "Enzymatic Synthesis of Modified Alternaria Mycotoxins Using a Whole-Cell Biotransformation System". Toxins 12, n. 4 (20 aprile 2020): 264. http://dx.doi.org/10.3390/toxins12040264.

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Reference standards for Alternaria mycotoxins are rarely available, especially the modified mycotoxins alternariol-3-glucoside (AOH-3-G), alternariol-9-glucoside (AOH-9-G), and alternariol monomethylether-3-glucoside (AME-3-G). To obtain these three glucosides as analytical standards for method development and method validation, alternariol and alternariol monomethylether were enzymatically glycosylated in a whole-cell biotransformation system using a glycosyltransferase from strawberry (Fragaria x ananassa), namely UGT71A44, expressed in Escherichia coli (E. coli). The formed glucosides were isolated, purified, and structurally characterized. The exact amount of the isolated compounds was determined using high-performance liquid chromatography with UV-detection (HPLC-UV) and quantitative nuclear resonance spectroscopy (qNMR). This method has proved to be highly effective with biotransformation rates of 58% for AOH-3-G, 5% for AOH-9-G, and 24% for AME-3-G.

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Song, Ji-Won, Joo-Hyun Seo, Doek-Kun Oh, Uwe T. Bornscheuer e Jin-Byung Park. "Design and engineering of whole-cell biocatalytic cascades for the valorization of fatty acids". Catalysis Science & Technology 10, n. 1 (2020): 46–64. http://dx.doi.org/10.1039/c9cy01802f.

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42

Jan, Malik, Sheng-Jie Yue, Ru-Xiang Deng, Yan-Fang Nie, Hong-Yan Zhang, Xiang-Rui Hao, Wei Wang, Hong-Bo Hu e Xue-Hong Zhang. "Aspergillus sclerotiorum Whole-Cell Biocatalysis: A Sustainable Approach to Produce 3-Hydroxy-phenazine 1-Carboxylic Acid from Phenazine 1-Carboxylic Acid". Fermentation 9, n. 6 (19 giugno 2023): 579. http://dx.doi.org/10.3390/fermentation9060579.

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In green chemistry, filamentous fungi are regarded as a kind of robust microorganism for the biotransformation of natural products. Nonetheless, the screening of microorganisms is crucial for the effective biotransformation of natural products, such as phenazine compounds. The precursor metabolite of most phenazine derivatives in Pseudomonas spp. is phenazine-1-carboxylic acid (PCA), the key constituent of shenqinmycin, widely used to control rice sheath blight in southern China. In this study, a new fungus strain Aspergillus sclerotiorum was isolated, which can efficiently convert PCA into 3-hydroxy-phenazine 1-carboxylic acid (3-OH-PCA). Moreover, an effective whole cells biotransformation system was designed by screening optimal reaction conditions and carbon sources. Hence, Aspergillus sclerotiorum exhibited desirable adaptation by the consumption of different carbon sources and maximum whole-cell biomass (10.6 g/L DCW) was obtained as a biocatalyst from glucose. Optimal conditions for whole-cell biocatalysis of PCA were evaluated, including a PCA concentration of 1120 mg/L, a pH of 7.0, a temperature of 25 °C, a rotation rate of 200 rpm, and dry cell weight of 15 g/L for 60 h; thus, 1060 mg/L of 3-OH-PCA was obtained and the conversion efficiency of PCA was 94%. Hence, the results of the repeated batch mood revealed that the biotransformation efficiency of fungus pellets reduced with each subsequent cycle, but remained stable in all five cycles with the provision of a glucose supplement. These findings present the prospect of using filamentous fungi for the whole-cell biocatalysis of phenazine in enormous amounts and the efficient production of 3-OH-PCA. Moreover, these results laid the foundation for further research to disclose the genetic-based mechanism of the strain responsible for PCA biotransformation.

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Iwaki, Hiroaki, Shaozhao Wang, Stephan Grosse, Hélène Bergeron, Ayako Nagahashi, Jittiwud Lertvorachon, Jianzhong Yang, Yasuo Konishi, Yoshie Hasegawa e Peter C. K. Lau. "Pseudomonad Cyclopentadecanone Monooxygenase Displaying an Uncommon Spectrum of Baeyer-Villiger Oxidations of Cyclic Ketones". Applied and Environmental Microbiology 72, n. 4 (aprile 2006): 2707–20. http://dx.doi.org/10.1128/aem.72.4.2707-2720.2006.

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ABSTRACT Baeyer-Villiger monooxygenases (BVMOs) are biocatalysts that offer the prospect of high chemo-, regio-, and enantioselectivity in the organic synthesis of lactones or esters from a variety of ketones. In this study, we have cloned, sequenced, and overexpressed in Escherichia coli a new BVMO, cyclopentadecanone monooxygenase (CpdB or CPDMO), originally derived from Pseudomonas sp. strain HI-70. The 601-residue primary structure of CpdB revealed only 29% to 50% sequence identity to those of known BVMOs. A new sequence motif, characterized by a cluster of charged residues, was identified in a subset of BVMO sequences that contain an N-terminal extension of ∼60 to 147 amino acids. The 64-kDa CPDMO enzyme was purified to apparent homogeneity, providing a specific activity of 3.94 μmol/min/mg protein and a 20% yield. CPDMO is monomeric and NADPH dependent and contains ∼1 mol flavin adenine dinucleotide per mole of protein. A deletion mutant suggested the importance of the N-terminal 54 amino acids to CPDMO activity. In addition, a Ser261Ala substitution in a Rossmann fold motif resulted in an improved stability and increased affinity of the enzyme towards NADPH compared to the wild-type enzyme (Km = 8 μM versus Km = 24 μM). Substrate profiling indicated that CPDMO is unusual among known BVMOs in being able to accommodate and oxidize both large and small ring substrates that include C11 to C15 ketones, methyl-substituted C5 and C6 ketones, and bicyclic ketones, such as decalone and β-tetralone. CPDMO has the highest affinity (Km = 5.8 μM) and the highest catalytic efficiency (k cat/Km ratio of 7.2 × 105 M−1 s−1) toward cyclopentadecanone, hence the Cpd designation. A number of whole-cell biotransformations were carried out, and as a result, CPDMO was found to have an excellent enantioselectivity (E > 200) as well as 99% S-selectivity toward 2-methylcyclohexanone for the production of 7-methyl-2-oxepanone, a potentially valuable chiral building block. Although showing a modest selectivity (E = 5.8), macrolactone formation of 15-hexadecanolide from the kinetic resolution of 2-methylcyclopentadecanone using CPDMO was also demonstrated.

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Fan, Lin-Lin, Hong-Ji Li e Qi-He Chen. "Applications and Mechanisms of Ionic Liquids in Whole-Cell Biotransformation". International Journal of Molecular Sciences 15, n. 7 (9 luglio 2014): 12196–216. http://dx.doi.org/10.3390/ijms150712196.

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Bader, Johannes, Edeltraud Mast-Gerlach e Ulf Stahl. "Controlled whole cell biotransformation by Gluconobacter oxydans under anaerobic conditions". Journal of Biotechnology 131, n. 2 (settembre 2007): S89. http://dx.doi.org/10.1016/j.jbiotec.2007.07.153.

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Baumgärtner, Florian, Lukas Jurzitza, Jürgen Conrad, Uwe Beifuss, Georg A. Sprenger e Christoph Albermann. "Synthesis of fucosylated lacto-N-tetraose using whole-cell biotransformation". Bioorganic & Medicinal Chemistry 23, n. 21 (novembre 2015): 6799–806. http://dx.doi.org/10.1016/j.bmc.2015.10.005.

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Klatte, Stephanie, e Volker F. Wendisch. "Redox self-sufficient whole cell biotransformation for amination of alcohols". Bioorganic & Medicinal Chemistry 22, n. 20 (ottobre 2014): 5578–85. http://dx.doi.org/10.1016/j.bmc.2014.05.012.

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Park, Su Ji, So Youn Youn, Geun Eog Ji e Myeong Soo Park. "Whole cell biotransformation of major ginsenosides using Leuconostocs and Lactobacilli". Food Science and Biotechnology 21, n. 3 (giugno 2012): 839–44. http://dx.doi.org/10.1007/s10068-012-0108-z.

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Vinciguerra, Vittorio, Alessandro D'Annibale, Eszter Gàcs-Baitz e Giuliano Delle Monache. "Biotransformation of tyrosol by whole-cell and cell-free preparation of Lentinus edodes". Journal of Molecular Catalysis B: Enzymatic 3, n. 5 (agosto 1997): 213–20. http://dx.doi.org/10.1016/s1381-1177(96)00061-6.

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Pfruender, Holger, Maya Amidjojo, Udo Kragl e Dirk Weuster-Botz. "Efficient Whole-Cell Biotransformation in a Biphasic Ionic Liquid/Water System". Angewandte Chemie International Edition 43, n. 34 (27 agosto 2004): 4529–31. http://dx.doi.org/10.1002/anie.200460241.

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