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Special Issue "Natural Product Enzymes in Biosynthesis and Biocatalysis"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Bioorganic Chemistry".

Deadline for manuscript submissions: closed (30 September 2018)

Special Issue Editor

Guest Editor
Prof. Dr. Tobias A. M. Gulder

Department of Chemistry and Center for Integrated Protein Science Munich (CIPSM), Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany
Website | E-Mail
Interests: natural product biosynthesis; biocatalysis; chemo-enzymatic synthesis; metabolic engineering

Special Issue Information

Dear Colleagues,

Nature provides a tremendous diversity of complex small molecules with intriguing strucutural and functional properties, in particular for biomedical applications. The biosynthetic machineries encoding these natural products are treasure troves for the discovery of valuable new enzymes catalyzing unprecedented transformations, ranging from highly regio- and stereoselective C-H-activation reactions to astonishing skelatal rearrangement sequences. In this Special Issue, we welcome research articles that take advantage of the arsenal of modern biomolecular and biochemical techniques to illuminate such biosynthetic transformations in vivo or in vitro and to utilize the respective proteins in biotechnological or chemo-enzymatic  applications.

As Guest Editor, I cordially invite researchers to submit their recent advances in the field to this Special Issue of Molecules.

With best regards,

Prof. Dr. Tobias A. M. Gulder
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Biosynthesis
  • Biotechnology
  • Biocatalysis
  • Enzymes
  • Enzyme Engineering
  • Pathway Engineering
  • Natural Products

Published Papers (3 papers)

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Research

Open AccessArticle Enzymatic Synthesis of Unnatural Ginsenosides Using a Promiscuous UDP-Glucosyltransferase from Bacillus subtilis
Molecules 2018, 23(11), 2797; https://doi.org/10.3390/molecules23112797
Received: 12 October 2018 / Revised: 24 October 2018 / Accepted: 25 October 2018 / Published: 28 October 2018
PDF Full-text (3004 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Glycosylation, which is catalyzed by UDP-glycosyltransferases (UGTs), is an important biological modification for the structural and functional diversity of ginsenosides. In this study, the promiscuous UGT109A1 from Bacillus subtilis was used to synthesize unnatural ginsenosides from natural ginsenosides. UGT109A1 was heterologously expressed in
[...] Read more.
Glycosylation, which is catalyzed by UDP-glycosyltransferases (UGTs), is an important biological modification for the structural and functional diversity of ginsenosides. In this study, the promiscuous UGT109A1 from Bacillus subtilis was used to synthesize unnatural ginsenosides from natural ginsenosides. UGT109A1 was heterologously expressed in Escherichia coli and then purified by Ni-NTA affinity chromatography. Ginsenosides Re, Rf, Rh1, and R1 were selected as the substrates to produce the corresponding derivatives by the recombinant UGT109A1. The results showed that UGT109A1 could transfer a glucosyl moiety to C3-OH of ginsenosides Re and R1, and C3-OH and C12-OH of ginsenosides Rf and Rh1, respectively, to produce unnatural ginsenosides 3,20-di-O-β-d-glucopyranosyl-6-O-[α-l-rhamnopyrano-(1→2)-β-d-glucopyranosyl]-dammar-24-ene-3β,6α,12β,20S-tetraol (1), 3,20-di-O-β-d-glucopyranosyl-6-O-[β-d-xylopyranosyl-(1→2)-β-d-glucopyranosyl]-dammar-24-ene-3β,6α,12β,20S-tetraol (6), 3-O-β-d-glucopyranosyl-6-O-[β-d-glucopyranosyl-(1→2)-β-d-glucopyranosyl]-dammar-24-ene-3β,6α,12β,20S-tetraol (3), 3,12-di-O-β-d-glucopyranosyl-6-O-[β-d-glucopyranosyl-(1→2)-β-d-glucopyranosyl]-dammar-24-ene-3β,6α,12β,20S-tetraol (2), 3,6-di-O-β-d-glucopyranosyl-dammar-24-ene-3β,6α,12β,20S-tetraol (5), and 3,6,12-tri-O-β-d-glucopyranosyl-dammar-24-ene-3β,6α,12β,20S-tetraol (4). Among the above products, 1, 2, 3, and 6 are new compounds. The maximal activity of UGT109A1 was achieved at the temperature of 40 °C, in the pH range of 8.0–10.0. The activity of UGT109A1 was considerably enhanced by Mg2+, Mn2+, and Ca2+, but was obviously reduced by Cu2+, Co2+, and Zn2+. The study demonstrated that UGT109A1 was effective in producing a series of unnatural ginsenosides through enzymatic reactions, which could pave a way to generate promising leads for new drug discovery. Full article
(This article belongs to the Special Issue Natural Product Enzymes in Biosynthesis and Biocatalysis)
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Graphical abstract

Open AccessArticle Optimization of Transesterification Reactions with CLEA-Immobilized Feruloyl Esterases from Thermothelomyces thermophila and Talaromyces wortmannii
Molecules 2018, 23(9), 2403; https://doi.org/10.3390/molecules23092403
Received: 27 August 2018 / Revised: 11 September 2018 / Accepted: 19 September 2018 / Published: 19 September 2018
PDF Full-text (4263 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Feruloyl esterases (FAEs, E.C. 3.1.1.73) are biotechnologically important enzymes with several applications in ferulic acid production from biomass, but also in synthesis of hydroxycinnamic acid derivatives. The use of such biocatalysts in commercial processes can become feasible by their immobilization, providing the advantages
[...] Read more.
Feruloyl esterases (FAEs, E.C. 3.1.1.73) are biotechnologically important enzymes with several applications in ferulic acid production from biomass, but also in synthesis of hydroxycinnamic acid derivatives. The use of such biocatalysts in commercial processes can become feasible by their immobilization, providing the advantages of isolation and recycling. In this work, eight feruloyl esterases, immobilized in cross-linked enzyme aggregates (CLEAs) were tested in regard to their transesterification performance, towards the production of prenyl ferulate (PFA) and arabinose ferulate (AFA). After solvent screening, comparison with the activity of respective soluble enzymes, and operational stability tests, FAE125 was selected as the most promising biocatalyst. A central composite design revealed the optimum conditions for each transesterification product, in terms of water content, time, and substrate ratio for both products, and temperature and enzyme load additionally for prenyl ferulate. The optimum product yields obtained were 83.7% for PFA and 58.1% for AFA. FAE125 CLEAs are stable in the optimum conditions of transesterification reactions, maintaining 70% residual activity after five consecutive reactions. Overall, FAE125 CLEAs seem to be able to perform as a robust biocatalyst, offering satisfactory yields and stability, and thus showing significant potential for industrial applications. Full article
(This article belongs to the Special Issue Natural Product Enzymes in Biosynthesis and Biocatalysis)
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Graphical abstract

Open AccessArticle Immobilized and Free Cells of Geotrichum candidum for Asymmetric Reduction of Ketones: Stability and Recyclability
Molecules 2018, 23(9), 2144; https://doi.org/10.3390/molecules23092144
Received: 25 July 2018 / Revised: 23 August 2018 / Accepted: 24 August 2018 / Published: 27 August 2018
PDF Full-text (1911 KB) | HTML Full-text | XML Full-text
Abstract
Marine-derived fungus Geotrichum candidum AS 2.361 was previously reported by our group as an active strain for the enantioselective reduction of ketones. Although some other Geotrichum strains were also found from the terrestrial sources, information on their stability and reusability is scarce. Herein,
[...] Read more.
Marine-derived fungus Geotrichum candidum AS 2.361 was previously reported by our group as an active strain for the enantioselective reduction of ketones. Although some other Geotrichum strains were also found from the terrestrial sources, information on their stability and reusability is scarce. Herein, the stabilities—in terms of pH tolerance, thermostability, and storage stability, and reusability—of G. candidum AS 2.361 were described for the asymmetric reduction of a series of aromatic ketones. Two differently immobilized cells (agar immobilization and calcium alginate immobilization) as well as free cells were prepared. For three substrates (1-(3-bromophenyl) ethan-1-one (1b), 1-(2-chlorophenyl) ethan-1-one (1d), and acetophenone (1g)) immobilized cells on agar showed a great improvement in the bioreduction activities compared to the free cells, increasing yields up to 97% with ee values of 99%. Cells immobilized on agar/calcium alginate could maintain more than 90% of the original activities within the assayed pH ranges of 3.5–11, while free cells were highly sensitive to alkaline and acidic conditions. Concerning thermostability, immobilized cells on agar kept 99% of their original activities after incubation at 60 °C for 1 h, while almost no activity was detected for the free cells under the same condition. Immobilized cells were stable at 4 °C for 80 days without any activity loss, while free cells started to decrease the activity after storage at 4 °C for six days. The immobilized cells retained almost 99% activity after four reuse cycles, while free cells lost almost all the activities at on the third cycle. Full article
(This article belongs to the Special Issue Natural Product Enzymes in Biosynthesis and Biocatalysis)
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