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Special Issue Editor

Prof. Dr. Lothar Elling

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

Dear Colleagues,

Glycans are parts of glycoconjugates (glycoproteins, glycolipids, proteoglycans) and are involved in numerous biological recognition events. Glycans are considered as encoding molecules. Maintaining, for example, cellular crosstalk at a molecular level is directly related to the vast chemical diversity of glycan structures. Glycan assembly by chemical and/or enzymatic synthesis is therefore challenging. Novel and efficient synthetic procedures for glycan-based products need to be developed and optimized. Especially, multienzyme cascade reactions are of great interest for the production of glycans at larger scales. Additionally, automated enzymatic synthesis of glycoconjugates is not far from realization. Protein engineering of enzymes leads to tailored biocatalysts with favorable and novel properties. Most importantly, the combination of chemo- and biocatalysis will expand the scope of novel routes for the synthesis of glycoconjugates. In this way, complex glycans and neo-glycoconjugates will be accessible for their application.

Decoding of glycan information by carbohydrate-recognizing molecules (lectins, antibodies, aptamers) is closely related to their multivalent glycan presentation on surface scaffolds—the glyco-biointerface. Monitoring the read-out of binding events can then be efficiently translated in diagnostic and therapeutic biomedical applications.

With this little overview, I cordially invite you to contribute and share your recent research results in this Special Issue on the synthesis and biological applications of glycoconjugates.

Prof. Dr. Lothar Elling
Guest Editor

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Published Papers (2 papers)

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Research

15 pages, 1526 KiB

Open AccessArticle

Oligosaccharide Ligands of Galectin-4 and Its Subunits: Multivalency Scores Highly

by Kristýna Slámová, Jakub Červený, Zuzana Mészáros, Tereza Friede, David Vrbata, Vladimír Křen and Pavla Bojarová

Molecules 2023, 28(10), 4039; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28104039 - 11 May 2023

Cited by 1 | Viewed by 1634

Abstract

Galectins are carbohydrate-binding lectins that modulate the proliferation, apoptosis, adhesion, or migration of cells by cross-linking glycans on cell membranes or extracellular matrix components. Galectin-4 (Gal-4) is a tandem-repeat-type galectin expressed mainly in the epithelial cells of the gastrointestinal tract. It consists of an N- and a C-terminal carbohydrate-binding domain (CRD), each with distinct binding affinities, interconnected with a peptide linker. Compared to other more abundant galectins, the knowledge of the pathophysiology of Gal-4 is sparse. Its altered expression in tumor tissue is associated with, for example, colon, colorectal, and liver cancers, and it increases in tumor progression, and metastasis. There is also very limited information on the preferences of Gal-4 for its carbohydrate ligands, particularly with respect to Gal-4 subunits. Similarly, there is virtually no information on the interaction of Gal-4 with multivalent ligands. This work shows the expression and purification of Gal-4 and its subunits and presents a structure–affinity relationship study with a library of oligosaccharide ligands. Furthermore, the influence of multivalency is demonstrated in the interaction with a model lactosyl-decorated synthetic glycoconjugate. The present data may be used in biomedical research for the design of efficient ligands of Gal-4 with diagnostic or therapeutic potential. Full article

(This article belongs to the Special Issue Synthesis and Biological Applications of Glycoconjugates Ⅲ)

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25 pages, 2912 KiB

Open AccessArticle

Characterization of Galectin Fusion Proteins with Glycoprotein Affinity Columns and Binding Assays

by Carina Dey, Philip Palm and Lothar Elling

Molecules 2023, 28(3), 1054; https://doi.org/10.3390/molecules28031054 - 20 Jan 2023

Viewed by 1876

Abstract

Galectins are β-galactosyl-binding proteins that fulfill essential physiological functions. In the biotechnological field, galectins are versatile tools, such as in the development of biomaterial coatings or the early-stage diagnosis of cancer diseases. Recently, we introduced galectin-1 (Gal-1) and galectin-3 (Gal-3) as fusion proteins of a His₆-tag, a SNAP-tag, and a fluorescent protein. We characterized their binding in ELISA-type assays and their application in cell-surface binding. In the present study, we have constructed further fusion proteins of galectins with fluorescent protein color code. The fusion proteins of Gal-1, Gal-3, and Gal-8 were purified by affinity chromatography. For this, we have prepared glycoprotein affinity resins based on asialofetuin (ASF) and fetuin and combined this in a two-step purification with Immobilized Metal Affinity chromatography (IMAC) to get pure and active galectins. Purified galectin fractions were analyzed by size-exclusion chromatography. The binding characteristics to ASF of solely His₆-tagged galectins and galectin fusion proteins were compared. As an example, we demonstrate a 1.6–3-fold increase in binding efficiency for HSYGal-3 (His₆-SNAP-yellow fluorescent protein-Gal-3) compared to the HGal-3 (His₆-Gal-3). Our results reveal an apparent higher binding efficiency for galectin SNAP-tag fusion proteins compared to His₆-tagged galectins, which are independent of the purification mode. This is also demonstrated by the binding of galectin fusion proteins to extracellular glycoconjugates laminin, fibronectin, and collagen IV. Our results indicate the probable involvement of the SNAP-tag in apparently higher binding signals, which we discuss in this study. Full article

(This article belongs to the Special Issue Synthesis and Biological Applications of Glycoconjugates Ⅲ)

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