Introduction of a human- and keyboard-friendly N-glycan nomenclature

• Friedrich Altmann,
• Johannes Helm,
• Martin Pabst and
• Johannes Stadlmann

Beilstein J. Org. Chem. 2024, 20, 607–620, doi:10.3762/bjoc.20.53

• supplanted by highly simplified terms for N-glycans that count the number of antennae or certain components such as galactoses, sialic acids and fucoses and give only limited room for exact structure description. The highly illustrative – and fortunately now standardized – cartoon depictions gained much

• known as linked to a beta-Gal residue, this lean annotation is unambiguous unless – very unexpectedly – a novel structural element turns up that makes this spelling invalid. Sialic acids – usually – are likewise linked to the β-galactose. Sialic acids may occur in the 3- or in the 6-position of this Gal

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• and straightforward as it is usually considered. Keywords: concentration; glycosylation; protecting groups; reactivity; sialic acids; stereoselectivity; Introduction Glycoconjugates containing sialic acid occur on the surface of all cell types in a variety of organisms. They participate in a broad

Shift of the reaction equilibrium at high pressure in the continuous synthesis of neuraminic acid

• Jannis A. Reich,
• Miriam Aßmann,
• Kristin Hölting,
• Paul Bubenheim,
• Jürgen Kuballa and
• Andreas Liese

Beilstein J. Org. Chem. 2022, 18, 567–579, doi:10.3762/bjoc.18.59

• is self-explanatory. Among them are sialic acids, which are produced and investigated for this reason, as they are found in cell membranes and play an important role in cell adhesion and signaling [1]. They are also studied, for instance, in Covid-19 research [2]. It has been pointed out that

• derivatives from Neu5Ac can inhibit viral enzymes [3]. Neu5Ac and its production have been described over the past three decades [4], however, no major breakthrough in its synthesis has been achieved so far [5]. Additionally, some reports underline the importance of sialic acids (rather than Neu5Ac in

Simulating the enzymes of ganglioside biosynthesis with Glycologue

• Andrew G. McDonald and
• Gavin P. Davey

Beilstein J. Org. Chem. 2021, 17, 739–748, doi:10.3762/bjoc.17.64

• since been rescinded [21].) To this base string are added a list of the sialic acids attached to each monosaccharide in the core, counting using the Roman numeral system, starting from the base glucose (cf. Figure 1). From the non-reducing end, write the position on the core where a sialic acid (or

• sialic acid chain) appears, as the uppercase Roman numeral, superscripting the linkage position after as the Arabic numeral, followed by “Neu5Ac”; if a chain of sialic acids is present, place the “Neu5Ac” in parentheses and subscript the number of residues after, e.g., IV3(Neu5Ac)2. Repeat this procedure

• for as many units of the core as are sialylated, separating with commas, then append a hyphen, followed by the core descriptor. The systematic Svennerholm nomenclature system used by Glycologue counts the total number of sialic acids in the carbohydrate, and appends this as a single letter (A: Asialo

Semiautomated glycoproteomics data analysis workflow for maximized glycopeptide identification and reliable quantification

• Steffen Lippold,
• Arnoud H. de Ru,
• Jan Nouta,
• Peter A. van Veelen,
• Magnus Palmblad,
• Manfred Wuhrer and
• Noortje de Haan

Beilstein J. Org. Chem. 2020, 16, 3038–3051, doi:10.3762/bjoc.16.253

• separation of glycopeptides in RPLC is mainly driven by the peptide portions. Thus, information on different proteins and glycosylation sites appears in the form of glycopeptide clusters. Next to the peptide portion, glycosylation features, such as sialic acids, can strongly influence the retention time [8

• [20]) within appropriate RT clusters (e.g., the same peptide portion and number of sialic acids). Furthermore, the user has the option to perform preprocessing steps, such as m/z calibration and RT alignment. For data curation, summed MS1 spectra were subjected to quality control based on user-defined

Automated high-content imaging for cellular uptake, from the Schmuck cation to the latest cyclic oligochalcogenides

• Rémi Martinent,
• Javier López-Andarias,
• Dimitri Moreau,
• Yangyang Cheng,
• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2020, 16, 2007–2016, doi:10.3762/bjoc.16.167

• attractive approach to tackle this central challenge [1][2][3][11][12][13][14]. The noncovalent interaction between the guanidinium cations from CPPs and cell membrane-associated anions, such as phospholipids, proteoglycans, or sialic acids, is considered to enhance the cell surface accumulation of

SnCl₄-catalyzed solvent-free acetolysis of 2,7-anhydrosialic acid derivatives

• Kesatebrhan Haile Asressu and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2019, 15, 2990–2999, doi:10.3762/bjoc.15.295

• thiosialoside and halide donors. Keywords: acetolysis; acetolysis products; 2,7-anhydrosialic acid; SnCl4; Introduction Sialic acids are the most prevalent monosaccharides that are found at the nonreducing ends of glycans, and they are involved in many biologically important ligand–receptor interactions [1

• galactosyl α(1→4) to Neu5Ac, and intramolecularly C-7-to-C-2-linked (via oxygen), forming 2,7-anhydro-Neu5Ac [4][5][6]. Owing to the substantial role of sialic acids in biological systems, numerous synthetic methods have been described in the literature [7][8][9][10][11][12][13][14][15][16]. 2,7-Anhydro

Cyclopropene derivatives of aminosugars for metabolic glycoengineering

• Jessica Hassenrück and
• Valentin Wittmann

Beilstein J. Org. Chem. 2019, 15, 584–601, doi:10.3762/bjoc.15.54

• reaction kinetics and their labeling intensities after metabolic incorporation. To determine the efficiencies by which the derivatives are metabolized to sialic acids, we synthesized and investigated the corresponding cyclopropane derivatives because cyclopropenes are not stable under the analysis

• bioorthogonal ligation reaction [5][6]. Mannosamine derivatives are of special interest because they are metabolized to sialic acids and then displayed as terminal structures on the cell surface [7]. Various carbohydrate derivatives with different reporter groups have been applied for MGE [2][3][4]. For example

• sialic acids that are labeled with a cyclopropene residue after MGE (i.e., the incorporation efficiency, IE). After the MGE experiments, we released the sialic acids from the cells by acetic acid treatment at elevated temperature and labeled them by addition of 1,2-diamino-4,5-methylenedioxybenzene (DMB

Lectins of Mycobacterium tuberculosis – rarely studied proteins

• Katharina Kolbe,
• Sri Kumar Veleti,
• Norbert Reiling and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2019, 15, 1–15, doi:10.3762/bjoc.15.1

• -galactopyranosides, L-fucopyranosides and sialic acids) that comprise the most terminal, and therefore most accessible for lectin recognition, oligosaccharide regions contribute to a vast diversity of possible glycocalyx structures [40][41][42]. It is known, for example, that the carbohydrate composition of the

Synthetic and semi-synthetic approaches to unprotected N-glycan oxazolines

• Antony J. Fairbanks

Beilstein J. Org. Chem. 2018, 14, 416–429, doi:10.3762/bjoc.14.30

• tolerant of other functional groups in the oligosaccharide, for example sialic acids [44] and phosphates [45][46] are completely unaffected; the former is perhaps rather surprising since DMC was first developed as a carboxylic acid activating agent for peptide synthesis by Ishikawa [47]! One caveat to the

• sialic acids can be removed by acidic hydrolysis [95], and the amine Fmoc protected. Branch specific exo-glycosidase digestion then allows the production of a wide variety of truncated glycans. Alternatively, by forming 4,6-benzylidenes of the mannose and galactose residues, acetylating all the remaining

• partially purified by acetone precipitation and extraction with 60% methanol. The crude N-glycans were found to be a rather complex mixture of compounds, the four major components of which were identified as triantennary glycans with 2 or 3 sialic acids attached as regioisomers (i.e., both α(2–6)- and α(2–3

Preactivation-based chemoselective glycosylations: A powerful strategy for oligosaccharide assembly

• Weizhun Yang,
• Bo Yang,
• Sherif Ramadan and
• Xuefei Huang

Beilstein J. Org. Chem. 2017, 13, 2094–2114, doi:10.3762/bjoc.13.207

• addition, one-pot protocols have been developed that have enabled multiple-step glycosylations in the same reaction flask without the need for intermediate purification. Complex glycans containing both 1,2-cis and 1,2-trans linkages, branched oligosaccharides, uronic acids, sialic acids, modifications such

Automated solid-phase synthesis of oligosaccharides containing sialic acids

• Chian-Hui Lai,
• Heung Sik Hahm,
• Chien-Fu Liang and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2015, 11, 617–621, doi:10.3762/bjoc.11.69

• -phase synthesis; Introduction N-Acetylneuraminic acid (sialic acid, Neu5Ac) is an important component of mammalian glycans and key to many recognition events of biomedical relevance including cell–cell recognition, signaling, and the immune response [1]. Sialic acids are present in tumor-associated

• latter linkage has to be incorporated either by using a preformed sialic acid–Gal disaccharide building block [11] or by enzymatic sialylation [27] following the cleavage and deprotection of an oligosaccharide. Terminal sialic acids are typically α-(2,3) or α-(2,6) linked to galactose (Gal) such as in

Expanding the scope of cyclopropene reporters for the detection of metabolically engineered glycoproteins by Diels–Alder reactions

• Anne-Katrin Späte,
• Verena F. Schart,
• Julia Häfner,
• Andrea Niederwieser,
• Thomas U. Mayer and
• Valentin Wittmann

Beilstein J. Org. Chem. 2014, 10, 2235–2242, doi:10.3762/bjoc.10.232

• metabolically engineered cell-surface sialic acids [24]. The application of 3 was prompted by the previous observation that carbamate-modified ManNAc derivatives are also accepted in the biosynthetic pathway [19][29]. Derivative 3 in combination with a sulfo-Cy3-tetrazine conjugate enabled dual sugar labeling

• by simultaneous DAinv reaction and strain-promoted azide–alkyne cycloaddition in a single step [24]. The potential of Ac4ManNCyoc (3) for labeling of sialoglycoconjugates was also recognized by others [30]. Sialic acids are prominently positioned at the outer end of membrane glycoproteins which makes

Carbohydrate PEGylation, an approach to improve pharmacological potency

• M. Eugenia Giorgi,
• Rosalía Agusti and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147

• as a biosensor of glucose [40]. A similar strategy was applied to the recombinant human thyroid-stimulating hormone (rhTSH, Thyrogen). Terminal sialic acids were oxidized with sodium periodate to generate aldehydes, which reacted with aminoxi-PEGs (Scheme 4B). The use of this PEGylating agent

Molecular recognition of surface-immobilized carbohydrates by a synthetic lectin

• Melanie Rauschenberg,
• Eva-Corrina Fritz,
• Christian Schulz,
• Tobias Kaufmann and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2014, 10, 1354–1364, doi:10.3762/bjoc.10.138

• calculations indicate that the interaction of the peptide with the carbohydrates is based primarily on hydrogen bonding [40]. It should be emphasized that NANA is a particularly interesting carbohydrate since it belongs to the class of sialic acids which are often the terminal carbohydrates in glycoproteins

• and glycolipids on the cell surface. Sialic acids are involved in the communication of cells with their environment [41] and selective detection, binding and blocking of sialic acids on the cell surface is of significant biomedical interest. It is the aim of this report to investigate whether the

Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C₂-symmetric building block: a strategy for the synthesis of decanolide natural products

• Bernd Schmidt and
• Oliver Kunz

Beilstein J. Org. Chem. 2013, 9, 2544–2555, doi:10.3762/bjoc.9.289

• approaches in the synthesis of target molecules from 1 or ent-1 include sialic acids [11], cladospolide C [12], iriomoteolide 3a [13][14], thromboxane B2 [15], didemniserinolipid B [16], squamostolide [17], muricatacine [18], rollicosin [19], phomopsolide C [7] and both enantiomers of seimatopolide A [20

An easily accessible sulfated saccharide mimetic inhibits in vitro human tumor cell adhesion and angiogenesis of vascular endothelial cells

• Grazia Marano,
• Claas Gronewold,
• Martin Frank,
• Anette Merling,
• Christian Kliem,
• Sandra Sauer,
• Manfred Wiessler,
• Eva Frei and
• Reinhard Schwartz-Albiez

Beilstein J. Org. Chem. 2012, 8, 787–803, doi:10.3762/bjoc.8.89

• -adhesive properties showed that 3,4-bis{[(β-D-galactopyranosyl)oxy]methyl}furan (BGF) could inhibit the adhesion of murine B16F10 melanoma cells to several ECM-proteins [15]. Probably, more important than uncharged saccharides are carbohydrates that contain acidic residues, such as sialic acids or sulfated

Bioorthogonal metabolic glycoengineering of human larynx carcinoma (HEp-2) cells targeting sialic acid

• Arne Homann,
• Riaz-ul Qamar,
• Sevnur Serim,
• Petra Dersch and
• Jürgen Seibel

Beilstein J. Org. Chem. 2010, 6, No. 24, doi:10.3762/bjoc.6.24

• Arne Homann Riaz-ul Qamar Sevnur Serim Petra Dersch Jurgen Seibel University of Würzburg, Department of Organic Chemistry, Am Hubland, 97074 Würzburg, Germany Helmholtz-Centre for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany 10.3762/bjoc.6.24 Abstract Sialic acids are located

• glycan structures of various types forming the individual, dynamic glycocalyx of each cell type. These glycolipids and glycoproteins often carry sialic acids, in humans N-acetylneuraminic acid (Neu5Ac, 1, Scheme 1), at their terminal position which mediate cell-cell recognition and signal transduction

• any significant background fluorescence (Figure 1). In both the Neu5Hex fed HEp-2 and the incubation with Ac4GlcNAz a clear staining of the cellular glycocalyx at the expected wavelengths was observed. Conclusion Sialic acids are prominent sugars which are located in the terminal position on cell