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Flexible Substrataufnahme aus Nährstoffreservoirs ist für Mikroorganismen entscheidend, um sich in kompetitiven natürlichen Umgebungen durchzusetzen. Zur Aufnahme von Glucose aus verschiedenen Glucosid‐ und Disaccharid‐Substraten haben viele frei‐ und symbiotisch lebende Bakterien, neben der Hydrolyse, einen nicht‐hydrolytischen Stoffwechselweg entwickelt. Dieser besteht aus vier biochemischen Schritten und wird von einem distinkten Genlocus (glycoside utilization locus, GUL) codiert. Mechanistisch integriert der Stoffwechselweg die Oxidation und Reduktion am Glucosyl/Glucose‐C3 mit der eliminativen Spaltung der glycosidischen Bindung und der Addition von Wasser an das Eliminationsprodukt in zwei aufeinanderfolgenden, von Lyasen katalysierten Reaktionen. In dieser Studie zeigen wir, basierend auf der Untersuchung von Enzymen des Pflanzenpathogens Agrobacterium tumefaciens, ein konserviertes Aktivitätszentrum in beiden Lyasen, welches um ein zentrales Mn2+ Metallion angeordnet ist. Weiters identifizieren wir die strukturellen Voraussetzungen für die spezifische Katalyse der 3‐Ketoglucosid Eliminierung zu 2‐Hydroxy‐3‐ketoglycal und der Hydratisierung des Glycal zu 3‐Ketoglucose. Die Erweiterung unserer Suche nach GUL‐codierten putativen Lyasen auf das menschliche darmkommensale Bakterium Bacteroides thetaiotaomicron führte uns zur Entdeckung eines Ca2+‐koordinierten Aktivitätszentrums in einem Glycosidase‐ähnlichen Protein. Das Enzym katalysiert die eliminative Spaltung von 3‐Ketoglucosiden entgegengesetzter (α) anomerer Konfiguration im Vergleich zu den von der A. tumefaciens Lyase präferierten Substraten (β). Strukturelle und biochemische Vergleiche zeigen die molekular‐mechanistische Basis der Stereokomplementarität der beiden 3‐Ketoglucosid Lyasen. Unsere Ergebnisse identifizieren ein grundlegendes Set von GUL‐codierten Lyasen für den Glucosidmetabolismus und erlauben es, der Gendiversität von GULs in der Domäne von Bakterien physiologische Bedeutung zuzuschreiben. [ABSTRACT FROM AUTHOR]

Der Nahrungsergänzungsmittelkonsum ist unter Sportlern aber auch in der Bevölkerung weit verbreitet. Das Angebot an Nahrungsergänzungsmitteln (NEM) hat in den letzten Jahren stark zugenommen. Vor dem Inverkehrbringen müssen NEM lediglich angezeigt werden. Eine Prüfung auf Wirksamkeit und Sicherheit findet, anders als bei Arzneimitteln, nicht statt und muss vom Hersteller gewährleistet werden. International werden NEM im Sport häufig in die Kategorien Sports Food, Medical Supplements und Performance Supplements unterteilt. Der folgende Beitrag soll einen Überblick über ausgewählte NEM geben. The consumption of dietary supplements is widespread among athletes but also among the population. The range of dietary supplements has increased significantly in recent years. Before being placed on the market, food supplements only need to be notified. In contrast to pharmaceuticals, there is no testing for efficacy and safety and must be guaranteed by the manufacturer. Internationally, food supplements in sports are often divided into the categories of sports food, medical supplements and performance supplements. The following article is intended to give an overview of selected food supplements. [ABSTRACT FROM AUTHOR]

Due to climate change, forest tree species are expected to be impacted by drought. As drought becomes a worldwide problem, there is a need to investigate the responses of forest tree species to drought. In this study, the objectives were (I) to determine the physiological and biochemical responses of seedlings grown from seeds obtained from different populations of Quercus petraea subsp. iberica naturally distributed in Turkey under drought stress, (II) to establish the relationships between morphological variations among populations and the physiological and biochemical responses of seedlings to drought stress, and (III) to provide recommendations for the selection of populations with better adaptation to drought for future afforestation activities. It was determined that total carotenoid, proline, and total carbohydrate contents increased, while predawn xylem water potential, chlorophyll a, chlorophyll b, and total chlorophyll amounts decreased in seedlings exposed to drought stress as the stress intensity increased. Furthermore, strong relationships were revealed between root percentage and Dickson quality index, which are important for seedling quality classification, and the physiological and biochemical responses of populations to drought stress. The populations of Alucra, Koyulhisar, and Mesudiye with water potential above -1.0 MPa during the drought stress experiment and experiencing more severe summer drought in their natural habitats have apparently exhibited higher drought tolerance compared to other populations. [ABSTRACT FROM AUTHOR]

Fucose ist ein signalgebendes Kohlenhydrat, das am Ende der Glykosylierung angehängt wird. Es ist an einer Reihe von Prozessen beteiligt, z. B. an der Selectin‐abhängigen Leukozytenadhäsion oder an Pathogen‐Rezeptor‐Interaktionen. Massenspektrometrische Verfahren, die üblicherweise zur Bestimmung der Struktur von Glykanen eingesetzt werden, zeigen häufig Fucose‐haltige, chimäre Fragmente, die die Analyse verzerren. Die Umlagerung, die zu diesen Fragmenten führt – oft als Fucose‐Migration bezeichnet – ist seit mehr als 25 Jahren bekannt, aber die chemische Identität des Umlagerungsproduktes bleibt unklar. In dieser Arbeit kombinieren wir Ionenmobilitätsspektrometrie, Massenspektrometrie mit radikalinduzierter Dissoziation, kryogene IR‐Spektroskopie und Computersimulationen mittels Dichtefunktionaltheorie, um das Produkt der Umlagerung der prototypischen Trisaccharide Lewis x und Blutgruppe H2 zu bestimmen. Die Struktursuche ergibt, dass die Fucose, die mit einer α(1→6)‐glykosidischen Bindung an die Galaktose gebunden ist, das wahrscheinlichste Produkt ist. [ABSTRACT FROM AUTHOR]

Summary Molisch's test is a test for carbohydrates which has the feature to differentiate between pentoses (arabinose, ribose, xylose), hexoses (e.g. glucose, galactose, fructose) and rhamnose, a deoxy sugar, via the colour shown. The use of α‐Naphthol as a solid has to be regarded as questionable. The risk potential of the experiment can be lowered via a reduced amount of applied chemicals thus leading to a thoroughly mixed solution instead of the normally formed ring in the test tube indicating a positive reaction. To further lower the risk potential of the reaction solid α‐Naphthol can be replaced by its ethanolic solution or the use of the natural compound Carvacrol. The implementation of these modifications yields a "new" colorful and meaningful Molisch test which can be used as an experiment for students with simple materials. [ABSTRACT FROM AUTHOR]

UDP‐Glucuronsäure(UDP‐GlcA)‐4‐Epimerase repräsentiert eine wichtige Fragestellung in der Enzymkatalyse: die Balance zwischen konformativer Flexibilität und genauer Positionierung. Das Enzym koordiniert die C4‐Oxidation des Substrats durch NAD+ mit der Rotation eines leicht decarboxylierbaren β‐Ketosäure‐Intermediats im aktiven Zentrum zur Ermöglichung der stereoinvertierenden Reduktion der Ketogruppe durch NADH. Wir zeigen hier die nur schwer erfassbare Rotationskoordinate des 4‐Ketointermediats. Distorsion des Zuckerrings in eine Boot‐Konformation erzeugt torsionale Mobilität in der Bindungstasche des Enzyms. Die Endpunkte der Rotation zeigen den 4‐Ketozucker in einer unverformten 4C1‐Sesselkonformation. Die äquatorial positionierte Carboxylatgruppe ist ungünstig für die 4‐Ketozucker‐Decarboxylierung. Varianten der Epimerase zeigen Decarboxylierung, wenn sie die Bindung mit der Carboxylatgruppe im entgegengesetzten Rotationsisomer des Substrats entfernen. R185A/D‐Substitutionen wandeln die Epimerase in UDP‐Xylose‐Synthasen um, welche UDP‐GlcA in stereospezifischen, konfigurationserhaltenden Reaktionen decarboxylieren. [ABSTRACT FROM AUTHOR]

Die automatisierte Glykan Assemblierung (AGA) auf festen Trägern ist heutzutage von unschätzbarem Wert, um die biologische Bedeutung komplexer Kohlenhydrate mit den anhaltenden Herausforderungen ihrer Synthese in Einklang zu bringen. Während AGA‐Plattformen die Konstruktion vieler natürlicher Zucker verändert haben, steckt die Validierung der Konstruktion wohldefinierter (positionsselektiv modifizierter) Glykomimetika noch in den Kinderschuhen. Motiviert durch die Bedeutung der Fluorierung in der Arzneimittelforschung, der biomedizinischen Bedeutung von 2‐Fluorzuckern und den bemerkenswerten Selektivitäten der fluorgesteuerten Glykosylierung, wird die Fluor‐dirigierte automatisierte Glykan Assemblierung (FDAGA) entwickelt. Diese Strategie nutzt das Fluoratom für die stereokontrollierte Glykosylierung auf einem festen Träger, wodurch die Abhängigkeit von O‐basierten dirigierenden Gruppen entfällt. Das logische Design von C2‐fluorierten Mannose‐Bausteinen und ihre Anwendung in der vollständig (α‐)stereoelektiven automatisierten Assemblierung von linearen und verzweigten fluorierten Oligomannosiden wird beschrieben. Diese Strategie kann in bestehende AGA‐ und Post‐AGA‐Protokolle integriert werden, um den Anwendungsbereich der programmierten Kohlenhydratsynthese zu erweitern. [ABSTRACT FROM AUTHOR]

Die Bildung von glykosidischen Bindungen ist eine ständige Herausforderung in der Praxis. Mit dem Ziel, die Reproduzierbarkeit und Effizienz der Synthese von Oligosacchariden zu verbessern, wird hier die Beziehung zwischen der Aktivierung des Glykosyl‐Donors und der Reaktionstemperatur untersucht. Ein neues semi‐automatisches Assay zeigt, dass die Mitglieder einer Gruppe von Thioglykoside unterschiedlich auf die Aktivierung bei verschiedenen Temperaturen reagieren. Die Muster der Schutzgruppen und des Thio‐Aglykons führen zu bemerkenswerten Unterschieden in der Temperaturempfindlichkeit der Glykosyl‐Donors. Wir führen das Konzept der Donor‐Aktivierungstemperatur ein, um experimentelle Erkenntnisse zu erfassen, und folgern daraus, dass Glykosylierungen, die unterhalb dieser Referenztemperatur durchgeführt werden, schädlichen Nebenreaktionen entgehen. Kentnisse über Aktivierungstemperaturen ermöglichen eine vereinfachte Temperaturbehandlung und erleichtern die Optimierung der Verwendung von Glykosyl‐Donors. Bei der isothermen Glykosylierung unterhalb der Aktivierungstemperatur halbierten sich die benötigten Bausteinäquivalente im Vergleich zu dem bisher in der Lösungs‐ und Festphasen‐Oligosaccharidsynthese verwendeten Standard‐"Rampen"‐Verfahren. [ABSTRACT FROM AUTHOR]

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Copyright of Gefaesschirurgie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Gefaesschirurgie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this experiment, the effects of two deficit irrigations (DI50, DI75) and full irrigation (FI100) together with control (Rainfed) treatment were evaluated. Irrigation was started when the midday leaf water potential reached −10 bars. Accordingly, irrigation was initiated after berry set and continued at weekly intervals until harvest time in the study area. To calculate water volumes applied to the irrigated plots, 50%, 75% and 100% of the cumulative evaporation from the class A pan for a week were considered. Considering gibberellic, salicylic and abscisic acid, organic acids, macro and micro elements, 'Carignane' had lower values than those of 'Semillon'. The amount of fructose, xylose and arabinose were higher in 'Carignane'. The amounts of all hormones, carbohydrates, organic acids and macro and micro elements were generally higher in control and DI50 treatments. But, no significant differences were found between irrigation levels considering hormones, indole acetic, citric, maleic and succinic acids. As a result of the study, it can be concluded that the amounts of compounds in the grape seeds increased with rainfed and deficit irrigation together with the rainfall under experimental conditions. [ABSTRACT FROM AUTHOR]

Copyright of German Journal of Sports Medicine / Deutsche Zeitschrift fur Sportmedizin is the property of Verein zur Forderung der Sportmedizin Hannover e.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The crystallization scheme in the sugar industry helps controlling the technological work in such a way that white sugar of the highest possible quality is obtained with the lowest possible energy input and the molasses produced is exhausted to the maximum. The yields achievable in the individual crystallization stages have a decisive influence on the design of the crystallization schemes. Other factors include the quality of the raw materials and the product requirements, as well as the available equipment and the chosen crystallization process. Selected examples are used to illustrate the latitude but also the practical limitations that arise in this area of conflict between quality requirements, yield, productivity and energy requirements for a sugar factory. [ABSTRACT FROM AUTHOR]

The lipopolysaccharide (LPS) O‐antigen structure of the plant pathogen Rhizobium radiobacter strain TT9 and its possible role in a plant‐microbe interaction was investigated. The analyses disclosed the presence of two O‐antigens, named Poly1 and Poly2. The repetitive unit of Poly2 constitutes a 4‐α‐l‐rhamnose linked to a 3‐α‐d‐fucose residue. Surprisingly, Poly1 turned out to be a novel type of biopolymer in which the repeating unit is formed by a monosaccharide and an amino‐acid derivative, so that the polymer has alternating glycosidic and amidic bonds joining the two units: 4‐amino‐4‐deoxy‐3‐O‐methyl‐d‐fucose and (2′R,3′R,4′S)‐N‐methyl‐3′,4′‐dihydroxy‐3′‐methyl‐5′‐oxoproline). Differently from the O‐antigens of LPSs from other pathogenic Gram‐negative bacteria, these two O‐antigens do not activate the oxidative burst, an early innate immune response in the model plant Arabidopsis thaliana, explaining at least in part the ability of this R. radiobacter strain to avoid host defenses during a plant infection process. [ABSTRACT FROM AUTHOR]

The recognition of either homomeric or heteromeric pairs of pentoses in an aromatic oligoamide double helical foldamer capsule was evidenced by circular dichroism (CD), NMR spectroscopy, and X‐ray crystallography. The cavity of the host was predicted to be large enough to accommodate simultaneously two xylose molecules and to form a 1:2 complex (one container, two saccharides). Solution and solid‐state data revealed the selective recognition of the α‐4C1‐d‐xylopyranose tautomer, which is bound at two identical sites in the foldamer cavity. A step further was achieved by sequestering a heteromeric pair of pentoses, that is, one molecule of α‐4C1‐d‐xylopyranose and one molecule of β‐1C4‐d‐arabinopyranose despite the symmetrical nature of the host and despite the similarity of the guests. Subtle induced‐fit and allosteric effects are responsible for the outstanding selectivities observed. [ABSTRACT FROM AUTHOR]

C‐Glycosides are both a common motif in many bioactive natural products and important glycoside mimetics. We demonstrate that activating a hemiacetal with a sulfonyl chloride, followed by treating the resultant glycosyl sulfonate with an enolate results in the stereospecific construction of β‐linked C‐glycosides. This reaction tolerates a range of acceptors and donors, including disaccharides. The resulting products can be readily derivatized into C‐glycoside analogues of β‐glycoconjugates, including C‐disaccharide mimetics. [ABSTRACT FROM AUTHOR]

A mild and convenient method for the synthesis of reverse glycosyl fluorides (RGFs) has been developed that is based on the silver‐promoted radical dehydroxymethylative fluorination of carbohydrates. A salient feature of the reaction is that furanoid and pyranoid carbohydrates furnish structurally diverse RGFs bearing a wide variety of functional groups in good to excellent yields. Intramolecular hydrogen atom transfer experiments revealed that the reaction involves an underexploited radical fluorination that proceeds via β‐fragmentation of sugar‐derived primary alkoxyl radicals. Structurally divergent RGFs were obtained by catalytic C−F bond activation, and our method thus offers a concise and efficient strategy for the synthesis of reverse glycosides by late‐stage diversification of RGFs. The potential of this method is showcased by the preparation and diversification of sotagliflozin, leading to the discovery of a promising SGLT2 inhibitor candidate. [ABSTRACT FROM AUTHOR]

The complex sulfation motifs of heparan sulfate glycosaminoglycans (HS GAGs) play critical roles in many important biological processes. However, an understanding of their specific functions has been hampered by an inability to synthesize large numbers of diverse, yet defined, HS structures. Herein, we describe a new approach to access the four core disaccharides required for HS/heparin oligosaccharide assembly from natural polysaccharides. The use of disaccharides rather than monosaccharides as minimal precursors greatly accelerates the synthesis of HS GAGs, providing key disaccharide and tetrasaccharide intermediates in about half the number of steps compared to traditional strategies. Rapid access to such versatile intermediates will enable the generation of comprehensive libraries of sulfated oligosaccharides for unlocking the "sulfation code" and understanding the roles of specific GAG structures in physiology and disease. [ABSTRACT FROM AUTHOR]

The receptor lipid Gb3 is responsible for the specific internalization of Shiga toxin (STx) into cells. The head group of Gb3 defines the specificity of STx binding, and the backbone with different fatty acids is expected to influence its localization within membranes impacting membrane organization and protein internalization. To investigate this influence, a set of Gb3 glycosphingolipids labeled with a BODIPY fluorophore attached to the head group was synthesized. C24 fatty acids, saturated, unsaturated, α‐hydroxylated derivatives, and a combination thereof, were attached to the sphingosine backbone. The synthetic Gb3 glycosphingolipids were reconstituted into coexisting liquid‐ordered (lo)/liquid‐disordered (ld) giant unilamellar vesicles (GUVs), and STx binding was verified by fluorescence microscopy. Gb3 with the C24:0 fatty acid partitioned mostly in the lo phase, while the unsaturated C24:1 fatty acid distributes more into the ld phase. The α‐hydroxylation does not influence its partitioning. [ABSTRACT FROM AUTHOR]

The fucosylation of glycans leads to diverse structures and is associated with many biological and disease processes. The exact determination of fucoside positions by tandem mass spectrometry (MS/MS) is complicated because rearrangements in the gas phase lead to erroneous structural assignments. Here, we demonstrate that the combined use of ion‐mobility MS and well‐defined synthetic glycan standards can prevent misinterpretation of MS/MS spectra and incorrect structural assignments of fucosylated glycans. We show that fucosyl residues do not migrate to hydroxyl groups but to acetamido moieties of N‐acetylneuraminic acid as well as N‐acetylglucosamine residues and nucleophilic sites of an anomeric tag, yielding specific isomeric fragment ions. This mechanistic insight enables the characterization of unique IMS arrival‐time distributions of the isomers which can be used to accurately determine fucosyl positions in glycans. [ABSTRACT FROM AUTHOR]

Stereocontrolled chemical glycosylation remains a major challenge despite vast efforts reported over many decades and so far still mainly relies on trial and error. Now it is shown that the relative reactivity value (RRV) of thioglycosides is an indicator for revealing stereoselectivities according to four types of acceptors. Mechanistic studies show that the reaction is dominated by two distinct intermediates: glycosyl triflates and glycosyl halides from N‐halosuccinimide (NXS)/TfOH. The formation of glycosyl halide is highly correlated with the production of α‐glycoside. These findings enable glycosylation reactions to be foreseen by using RRVs as an α/β‐selectivity indicator and guidelines and rules to be developed for stereocontrolled glycosylation. [ABSTRACT FROM AUTHOR]

The direct 2‐deoxyglycosylation of nucleophiles with glycals leads to biologically and pharmacologically important 2‐deoxysugar compounds. Although the direct addition of hydroxyl and sulfonamide groups have been well developed, the direct 2‐deoxyglycosylation of amide groups has not been reported to date. Herein, we show the first direct 2‐deoxyglycosylation of amide groups using a newly designed Brønsted acid catalyst under mild conditions. Through mechanistic investigations, we discovered that the amide group can inhibit acid catalysts, and the inhibition has made the 2‐deoxyglycosylation reaction difficult. Diffusion‐ordered two‐dimensional NMR spectroscopy analysis implied that the 2‐chloroazolium salt catalyst was less likely to form aggregates with amides in comparison to other acid catalysts. The chlorine atom and the extended π‐scaffold of the catalyst played a crucial role for this phenomenon. This relative insusceptibility to inhibition by amides is more responsible for the catalytic activity than the strength of the acidity. [ABSTRACT FROM AUTHOR]

A dense hydrogen‐bond network is responsible for the mechanical and structural properties of polysaccharides. Random derivatization alters the properties of the bulk material by disrupting the hydrogen bonds, but obstructs detailed structure–function correlations. We have prepared well‐defined unnatural oligosaccharides including methylated, deoxygenated, deoxyfluorinated, as well as carboxymethylated cellulose and chitin analogues with full control over the degree and pattern of substitution. Molecular dynamics simulations and crystallographic analysis show how distinct hydrogen‐bond modifications drastically affect the solubility, aggregation behavior, and crystallinity of carbohydrate materials. This systematic approach to establishing detailed structure–property correlations will guide the synthesis of novel, tailor‐made carbohydrate materials. [ABSTRACT FROM AUTHOR]

Carbohydrates are attached and removed in living systems through the action of carbohydrate‐active enzymes such as glycosyl transferases and glycoside hydrolases. The molecules resulting from these enzymes have many important roles in organisms, such as cellular communication, structural support, and energy metabolism. In general, each carbohydrate transformation requires a separate catalyst, and so these enzyme families are extremely diverse. To make this diversity manageable, high‐throughput approaches look at many enzymes at once. Similarly, high‐throughput approaches can be a powerful way of finding inhibitors that can be used to tune the reactivity of these enzymes, either in an industrial, a laboratory, or a medicinal setting. In this review, we provide an overview of how these enzymes and inhibitors can be sought using techniques such as high‐throughput natural product and combinatorial library screening, phage and mRNA display of (glyco)peptides, fluorescence‐activated cell sorting, and metagenomics. [ABSTRACT FROM AUTHOR]

The site‐selective functionalization of carbohydrates is an active area of research. Reported here is the surprising observation that the sterically encumbered adamantyl group directed site‐selective acylation at the C2 position of S‐glycosides through dispersion interactions between the adamantyl C−H bonds and the π system of the cationic acylated catalyst, which may have broad implications in many other chemical reactions. Because of their stability, chemical orthogonality, and ease of activation for glycosylation, the site‐selective acylation of S‐glycosides streamlines oligosaccharide synthesis and will have wide applications in complex carbohydrate synthesis. [ABSTRACT FROM AUTHOR]

The tremendous isomeric diversity of carbohydrates enables a wide range of their biological functions but makes the identification and study of these molecules difficult. We investigated the ability of intermolecular interactions to communicate structural specificity of carbohydrates to protonated aromatic molecules in non‐covalent complexes, isolated and cooled in the gas phase. Our study revealed that small structural differences between carbohydrate isomers of any type, including enantiomers, are accurately communicated by these interactions to aromatic molecules as detectable changes in their electronic excitation spectra. The specific response of the aromatics to the isomers of carbohydrates is fine‐tuned by the interplay of the various involved non‐covalent bonds. These findings enable the gas‐phase identification and relative quantification of any isomers of oligosaccharides in their solution mixtures using the 2D UV‐MS fingerprinting technique. [ABSTRACT FROM AUTHOR]

Carbohydrates are the major component of biomass and have unique potential as a sustainable source of building blocks for chemicals, materials, and biofuels because of their low cost, ready availability, and stereochemical diversity. With a view to upgrading carbohydrates to access valuable nitrogen‐containing sugar‐like compounds such as aminopolyols, biocatalytic aminations using transaminase enzymes (TAms) have been investigated as a sustainable alternative to traditional synthetic strategies. Demonstrated here is the reaction of TAms with sugar‐derived tetrahydrofuran (THF) aldehydes, obtained from the regioselective dehydration of biomass‐derived sugars, to provide access to cyclic aminodiols in high yields. In a preliminary study we have also established the direct transamination of sugars to give acyclic aminopolyols. Notably, the reaction of the ketose d‐fructose proceeds with complete stereoselectivity to yield valuable aminosugars in high purity. [ABSTRACT FROM AUTHOR]

A de novo synthetic strategy for the production of oligosaccharides containing 2,3,6‐trideoxypyranoglycoside is reported. The key event is the Pd‐catalyzed asymmetric diastereoselective hydroalkoxylation of ene‐alkoxyallene‐linked glycosidic fragments. The utility of this approach was demonstrated by the activation‐free, stereodivergent, and convergent synthesis of various 2‐deoxyoligosaccharides, as well as their aglycon conjugates. [ABSTRACT FROM AUTHOR]

Rosemary is one of the most important medicinal plants. In order to study the effect of plant growth promoting rhizobacteria (PGPR), Azolla compost and Azolla biochar on dry matter, nutrient uptake, physiological parameters and essential oil of rosemary, a greenhouse experiment was conducted in a completely randomized design with 6 replications. Treatments consisted of T1 (control), T2 (1% (1 g 100 g-1 dry soil) Azolla compost), T3 (1% Azolla biochar), T4 (PGPR (P. fluorescens)), T5 (1% compost + PGPR) and T6 (1% biochar + PGPR). Results indicated a significant enhancement of dry matter, nutrient uptake, photosynthetic pigments, carbohydrate, flavonoid and essential oil contents of rosemary influenced by organic fertilizers compared to control, particularly with co-application of PGPR + compost or biochar. Proline content decreased in all treatments in comparison with control. Results indicated positive impacts of PGPR, compost and boichar of Azolla on rosemary production by increasing nutrient uptake and protecting chlorophyll from degradation and enhancing its content in leaves. [ABSTRACT FROM AUTHOR]

Glykoinformatik ist eine sich aktiv entwickelnde wissenschaftliche Disziplin, die Wissenschaftlern den Zugang zu den Daten über natürliche Glykane und zu verschiedenen Datenverarbeitungswerkzeugen ermöglicht. Die Informatisierung der Glykomik hat jedoch noch einen langen Weg vor sich, bevor sie zur Genomik und Proteomik aufschließen wird. In diesem Standpunkt wird die aktuelle in Situation der Glykoinformatik betrachtet und ihre Errungenschaften und Mängel diskutiert, wobei die größten Nachteile hervorgehoben werden: das Fehlen anerkannter Standards, Protokolle, Datenindizes und ‐werkzeuge sowie die informationstechnologische Isoliertheit der bestehenden Projekte. Wir reiterieren mögliche Lösungen der anhaltenden Probleme und beschreiben unsere Vision eines idealen Glykoinformatik‐Projekts. Eine Frage der Organisation: Trotz der grundlegenden Bedeutung von Kohlenhydraten für lebende Organismen ist die Informatisierung von „Glycomics" noch lange nicht abgeschlossen. Der Mangel an anerkannten Standards, Datenbanken, Protokollen und Werkzeugen sowie eine begrenzte Vernetzung der bestehenden Projekte sowohl untereinander als auch mit den globalen Lebenswissenschaften verhindert eine erfolgreiche Anwendung der Glykoinformatik in der modernen Forschung. [ABSTRACT FROM AUTHOR]

Stereospecific β‐l‐rhamnopyranosylations were conducted using a 1,2‐anhydro‐l‐rhamnopyranose donor and mono‐ol or diol acceptors in the presence of a glycosyl‐acceptor‐derived borinic or boronic ester. Reactions proceeded smoothly to provide the corresponding β‐l‐rhamnopyranosides (β‐l‐Rhap) with complete stereoselectivity in moderate to high yields without any further additives under mild conditions. Mechanistic studies of the borinic ester mediated glycosylation using 13C kinetic isotope effect (KIE) measurements and DFT calculations were consistent with a concerted SNi mechanism with an exploded transition state. In addition, the present glycosylation method was applied successfully to the synthesis of a trisaccharide, α‐l‐Rhap‐(1,2)‐β‐l‐Rhap‐(1,4)‐Glcp, derived from Streptococcus pneumoniae serotypes 7B, 7C, and 7D. [ABSTRACT FROM AUTHOR]

Abstract: Xylobiose sequestration in a helical aromatic oligoamide capsule was evidenced by circular dichroism, NMR spectroscopy, and crystallography. The preparation of the 5 kDa oligoamide sequence was made possible by the transient use of acid‐labile dimethoxybenzyl tertiary amide substituents that disrupt helical folding and prevent double helix formation. Binding of other disaccharides was not detected. Crystallographic data revealed a complex composed of a d‐xylobiose α anomer and two water molecules accommodated in the right‐handed helix. The disaccharide was found to adopt an unusual all‐axial compact conformation. A dense network of 18 hydrogen bonds forms between the guest, the cavity wall, and the two water molecules. [ABSTRACT FROM AUTHOR]

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There is currently an urgent need for the development of new antibacterial agents to combat the spread of antibiotic‐resistant bacteria. We explored the synthesis and antibacterial activities of novel, sugar‐functionalized phosphonium polymers. While these compounds exhibited antibacterial activity, we unexpectedly found that the control polymer poly(tris(hydroxypropyl)vinylbenzylphosphonium chloride) showed very high activity against both Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus and very low haemolytic activity against red blood cells. These results challenge the conventional wisdom in the field that lipophilic alkyl substituents are required for high antibacterial activity and opens prospects for new classes of antibacterial polymers. [ABSTRACT FROM AUTHOR]

Abstract: The heterogeneous nature of non‐cellulosic polysaccharides, such as arabinoxylan, makes it difficult to correlate molecular structure with macroscopic properties. To study the impact of specific structural features of the polysaccharides on crystallinity or affinity to other cell wall components, collections of polysaccharides with defined repeating units are required. Herein, a chemoenzymatic approach to artificial arabinoxylan polysaccharides with systematically altered branching patterns is described. The polysaccharides were obtained by glycosynthase‐catalyzed polymerization of glycosyl fluorides derived from arabinoxylan oligosaccharides. X‐ray diffraction and adsorption experiments on cellulosic surfaces revealed that the physicochemical properties of the synthetic polysaccharides strongly depend on the specific nature of their substitution patterns. The artificial polysaccharides allow structure–property relationship studies that are not accessible by other means. [ABSTRACT FROM AUTHOR]

Abstract: The macrocyclic antibiotic mangrolide A has been described to exhibit potent activity against a number of clinically important Gram‐negative pathogens. Reported is the first enantioselective total synthesis of mangrolide A and derivatives. Salient features of this synthesis include a highly convergent macrocycle preparation, stereoselective synthesis of the disaccharide moiety, and two β‐selective glycosylations. The synthesis of mangrolide A and its analogues enabled the re‐examination of its activity against bacterial pathogens, and only minimal activity was observed. [ABSTRACT FROM AUTHOR]

Abstract: O Mannosylation is a vital protein modification involved in brain and muscle development whereas the biological relevance of O‐mannosyl glycans has remained largely unknown owing to the lack of structurally defined glycoforms. An efficient scaffold synthesis/enzymatic extension (SSEE) strategy was developed to prepare such structures by combining gram‐scale convergent chemical syntheses of three scaffolds and strictly controlled sequential enzymatic extension catalyzed by glycosyltransferases. In total, 45 O‐mannosyl glycans were obtained, covering the majority of identified mammalian structures. Subsequent glycan microarray analysis revealed fine specificities of glycan‐binding proteins and specific antisera. [ABSTRACT FROM AUTHOR]

Abstract: Sialyl‐Tn (STn) is a tumor‐associated carbohydrate antigen (TACA) rarely observed on healthy tissues. We synthesized two fully synthetic N‐acetyl and N‐propionyl STn trimer (triSTn) vaccines possessing a T‐helper epitope and a TLR2 agonist, since the clustered STn antigens are highly expressed on many cancer cells. Immunization of both vaccines in mice induced the anti‐triSTn IgG antibodies, which recognized triSTn‐expressing cell lines PANC‐1 and HepG2. The N‐propionyl triSTn vaccine induced the triSTn‐specific IgGs, while IgGs induced by the N‐acetyl triSTn vaccine were less specific. These results illustrated that N‐propionyl triSTn is a valuable unnatural TACA for anticancer vaccines. [ABSTRACT FROM AUTHOR]