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Special Issue "Synthesis and Biological Applications of Glycoconjugates Ⅱ"

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

Deadline for manuscript submissions: closed (1 April 2019)

Special Issue Editor

Guest Editor
Prof. Dr. Lothar Elling

Laboratory for Biomaterials, Institute of Biotechnology and Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstraße 20, 52074 Aachen, Germany
Website | E-Mail
Interests: glycoconjugates; enzyme cascade reactions; chemo-enzymatic synthesis; glycosyltransferases; nucleotide sugars; galectins; lectins; glycopolymers; biosensors; biomaterials

Special Issue Information

Dear Colleagues,

Glycoconjugates (glycoproteins, glycolipids, proteoglycans) are involved in numerous biological recognition events. Their glycans encode the specific information to trigger protein–glycan interactions. Intercellular crosstalk and pathogen–host interactions are examples and are directly related to the vast chemical diversity of glycan structures. Glycan synthesis via chemical and/or enzymatic approaches are therefore challenging. Novel and efficient procedures for glycan-based products need to be developed and optimized. Multi-enzyme cascade reactions are key for the production of glycans in a larger scale. Protein engineering of enzymes serve to tailor biocatalysts with favorable and novel properties. Most importantly, the combination of chemo- and biocatalysis expands the spectrum of novel synthetic routes. In this way, complex glycans and neo-glycoconjugates will be accessible for biological applications. Multivalency is a key factor for decoding glycan information by carbohydrate recognizing molecules such as lectins and antibodies leading to many applications in biomedicine, biomaterial research, and advanced material sciences. Examples have been seen already in the first Special Issue “Synthesis and Biological Applications of Glycoconjugates” in Molecules in 2017.

I cordially invite you to contribute and share your recent research results in the upcoming second Special Issue on all aspects of the synthesis and biological applications of glycoconjugates.

Prof. Dr. Lothar Elling
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.

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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

  • glycoproteins
  • glycolipids
  • proteoglycans
  • biocatalysis
  • cascade reactions
  • chemo-enzymatic synthesis
  • lectins
  • biomaterials
  • glycopolymers
  • biosensors
  • glycoconjugates in tissue engineering
  • glycoconjugates of the microbiome
  • glycoconjugates in host-pathogen interaction

Related Special Issue

Published Papers (5 papers)

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Research

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Open AccessArticle Enzymatic Synthesis of Trideuterated Sialosides
Molecules 2019, 24(7), 1368; https://doi.org/10.3390/molecules24071368
Received: 28 February 2019 / Revised: 29 March 2019 / Accepted: 2 April 2019 / Published: 8 April 2019
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Abstract
Sialic acids are a family of acidic monosaccharides often found on the termini of cell surface proteins or lipid glycoconjugates of higher animals. Herein we describe the enzymatic synthesis of the two isotopically labeled sialic acid derivatives d3-X-Gal-α-2,3-Neu5Ac and d3 [...] Read more.
Sialic acids are a family of acidic monosaccharides often found on the termini of cell surface proteins or lipid glycoconjugates of higher animals. Herein we describe the enzymatic synthesis of the two isotopically labeled sialic acid derivatives d3-X-Gal-α-2,3-Neu5Ac and d3-X-Gal-α-2,3-Neu5Gc. Using deuterium oxide as the reaction solvent, deuterium atoms could be successfully introduced during the enzymatic epimerization and aldol addition reactions when the sialosides were generated. NMR and mass spectrometric analyses confirmed that the resulting sialosides were indeed tri-deuterated. These compounds may be of interest as internal standards in liquid chromatography/mass spectrometric assays for biochemical or clinical studies of sialic acids. This was further exemplified by the use of this tri-deuterated sialosides as internal standards for the quantification of sialic acids in meat and egg samples. Full article
(This article belongs to the Special Issue Synthesis and Biological Applications of Glycoconjugates Ⅱ)
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Open AccessArticle Identification of Leishmania major UDP-Sugar Pyrophosphorylase Inhibitors Using Biosensor-Based Small Molecule Fragment Library Screening
Molecules 2019, 24(5), 996; https://doi.org/10.3390/molecules24050996
Received: 29 January 2019 / Revised: 4 March 2019 / Accepted: 7 March 2019 / Published: 12 March 2019
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Abstract
Leishmaniasis is a neglected disease that is caused by different species of the protozoan parasite Leishmania, and it currently affects 12 million people worldwide. The antileishmanial therapeutic arsenal remains very limited in number and efficacy, and there is no vaccine for this [...] Read more.
Leishmaniasis is a neglected disease that is caused by different species of the protozoan parasite Leishmania, and it currently affects 12 million people worldwide. The antileishmanial therapeutic arsenal remains very limited in number and efficacy, and there is no vaccine for this parasitic disease. One pathway that has been genetically validated as an antileishmanial drug target is the biosynthesis of uridine diphosphate-glucose (UDP-Glc), and its direct derivative UDP-galactose (UDP-Gal). De novo biosynthesis of these two nucleotide sugars is controlled by the specific UDP-glucose pyrophosphorylase (UGP). Leishmania parasites additionally express a UDP-sugar pyrophosphorylase (USP) responsible for monosaccharides salvage that is able to generate both UDP-Gal and UDP-Glc. The inactivation of the two parasite pyrophosphorylases UGP and USP, results in parasite death. The present study reports on the identification of structurally diverse scaffolds for the development of USP inhibitors by fragment library screening. Based on this screening, we selected a small set of commercially available compounds, and identified molecules that inhibit both Leishmania major USP and UGP, with a half-maximal inhibitory concentration in the 100 µM range. The inhibitors were predicted to bind at allosteric regulation sites, which were validated by mutagenesis studies. This study sets the stage for the development of potent USP inhibitors. Full article
(This article belongs to the Special Issue Synthesis and Biological Applications of Glycoconjugates Ⅱ)
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Open AccessArticle The β-N-Acetylhexosaminidase in the Synthesis of Bioactive Glycans: Protein and Reaction Engineering
Molecules 2019, 24(3), 599; https://doi.org/10.3390/molecules24030599
Received: 13 January 2019 / Revised: 4 February 2019 / Accepted: 6 February 2019 / Published: 8 February 2019
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Abstract
N-Acetylhexosamine oligosaccharides terminated with GalNAc act as selective ligands of galectin-3, a biomedically important human lectin. Their synthesis can be accomplished by β-N-acetylhexosaminidases (EC 3.2.1.52). Advantageously, these enzymes tolerate the presence of functional groups in the substrate molecule, such as [...] Read more.
N-Acetylhexosamine oligosaccharides terminated with GalNAc act as selective ligands of galectin-3, a biomedically important human lectin. Their synthesis can be accomplished by β-N-acetylhexosaminidases (EC 3.2.1.52). Advantageously, these enzymes tolerate the presence of functional groups in the substrate molecule, such as the thiourea linker useful for covalent conjugation of glycans to a multivalent carrier, affording glyconjugates. β-N-Acetylhexosaminidases exhibit activity towards both N-acetylglucosamine (GlcNAc) and N-acetylgalactosamine (GalNAc) moieties. A point mutation of active-site amino acid Tyr into other amino acid residues, especially Phe, His, and Asn, has previously been shown to strongly suppress the hydrolytic activity of β-N-acetylhexosaminidases, creating enzymatic synthetic engines. In the present work, we demonstrate that Tyr470 is an important mutation hotspot for altering the ratio of GlcNAcase/GalNAcase activity, resulting in mutant enzymes with varying affinity to GlcNAc/GalNAc substrates. The enzyme selectivity may additionally be manipulated by altering the reaction medium upon changing pH or adding selected organic co-solvents. As a result, we are able to fine-tune the β-N-acetylhexosaminidase affinity and selectivity, resulting in a high-yield production of the functionalized GalNAcβ4GlcNAc disaccharide, a selective ligand of galectin-3. Full article
(This article belongs to the Special Issue Synthesis and Biological Applications of Glycoconjugates Ⅱ)
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Open AccessArticle Screening of a Library of Oligosaccharides Targeting Lectin LecB of Pseudomonas Aeruginosa and Synthesis of High Affinity Oligoglycoclusters
Molecules 2018, 23(12), 3073; https://doi.org/10.3390/molecules23123073
Received: 29 October 2018 / Revised: 15 November 2018 / Accepted: 21 November 2018 / Published: 24 November 2018
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Abstract
The Gram negative bacterium Pseudomonas aeruginosa (PA) is an opportunistic bacterium that causes severe and chronic infection of immune-depressed patients. It has the ability to form a biofilm that gives a selective advantage to the bacteria with respect to antibiotherapy and host defenses. [...] Read more.
The Gram negative bacterium Pseudomonas aeruginosa (PA) is an opportunistic bacterium that causes severe and chronic infection of immune-depressed patients. It has the ability to form a biofilm that gives a selective advantage to the bacteria with respect to antibiotherapy and host defenses. Herein, we have focused on the tetrameric soluble lectin which is involved in bacterium adherence to host cells, biofilm formation, and cytotoxicity. It binds to l-fucose, d-mannose and glycan exposing terminal fucose or mannose. Using a competitive assay on microarray, 156 oligosaccharides and polysaccharides issued from fermentation or from the biomass were screened toward their affinity to LecB. Next, the five best ligands (Lewisa, Lewisb, Lewisx, siayl-Lewisx and 3-fucosyllactose) were derivatized with a propargyl aglycon allowing the synthesis of 25 trivalent, 25 tetravalent and 5 monovalent constructions thanks to copper catalyzed azide alkyne cycloaddition. The 55 clusters were immobilized by DNA Directed immobilization leading to the fabrication of a glycocluster microarray. Their binding to LecB was studied. Multivalency improved the binding to LecB. The binding structure relationship of the clusters is mainly influenced by the carbohydrate residues. Molecular simulations indicated that the simultaneous contact of both binding sites of monomer A and D seems to be energetically possible. Full article
(This article belongs to the Special Issue Synthesis and Biological Applications of Glycoconjugates Ⅱ)
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Review

Jump to: Research

Open AccessFeature PaperReview Glycopeptides and -Mimetics to Detect, Monitor and Inhibit Bacterial and Viral Infections: Recent Advances and Perspectives
Molecules 2019, 24(6), 1004; https://doi.org/10.3390/molecules24061004
Received: 15 February 2019 / Revised: 6 March 2019 / Accepted: 7 March 2019 / Published: 13 March 2019
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Abstract
The initial contact of pathogens with host cells is usually mediated by their adhesion to glycan structures present on the cell surface in order to enable infection. Furthermore, glycans play important roles in the modulation of the host immune responses to infection. Understanding [...] Read more.
The initial contact of pathogens with host cells is usually mediated by their adhesion to glycan structures present on the cell surface in order to enable infection. Furthermore, glycans play important roles in the modulation of the host immune responses to infection. Understanding the carbohydrate-pathogen interactions are of importance for the development of novel and efficient strategies to either prevent, or interfere with pathogenic infection. Synthetic glycopeptides and mimetics thereof are capable of imitating the multivalent display of carbohydrates at the cell surface, which have become an important objective of research over the last decade. Glycopeptide based constructs may function as vaccines or anti-adhesive agents that interfere with the ability of pathogens to adhere to the host cell glycans and thus possess the potential to improve or replace treatments that suffer from resistance. Additionally, synthetic glycopeptides are used as tools for epitope mapping of antibodies directed against structures present on various pathogens and have become important to improve serodiagnostic methods and to develop novel epitope-based vaccines. This review will provide an overview of the most recent advances in the synthesis and application of glycopeptides and glycopeptide mimetics exhibiting a peptide-like backbone in glycobiology. Full article
(This article belongs to the Special Issue Synthesis and Biological Applications of Glycoconjugates Ⅱ)
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