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This publication reports a facile and convenient preparation of tri-O-acetyl-glucopyranoses, derived from the corresponding 2-deoxyaminosugar, where the vicinal anomeric and C2 positions are decorated by azido and (thio)ureido groups, respectively. This double functionalization leads to an inherently chiral core incorporating the versatile azido and (thio)ureido linkages prone to further manipulation. The latter also provides a structural element for hydrogen-bonded donor-acceptor (HB-DA) sites, which are of immense value in organocatalytic pursuits. A computation-aided conformational analysis unveils the landscape of available conformers and their relative stability. N-aryl (thio)ureas bearing substituents at ortho positions exist as mixtures of M- and P-atropisomeric conformers. [ABSTRACT FROM AUTHOR]

The LebLea heptasaccharide is a tumor-associated carbohydrate antigen that was isolated from the human colonic adenocarcinoma cell line Colo205 and is a good target for the development of anti-cancer immunotherapeutics. However, it displays on its reducing end the Leb tetrasaccharide: α-l-Fucp-(1→2)-β-d-Galp-(1→3)-[α-l-Fucp-(1→4)]-d-GlcNAcp and the H-type 1 (H-1 antigen) trisaccharide: α-l-Fucp-(1→2)-β-d-Galp-(1→3)-d-GlcNAcp that are also found on noncancerous tissues. To discover analogues or fragments of LebLea that could be used as immunotherapeutics while not triggering immune responses against Leb and the H-1 antigen, we have synthesized the Leb tetrasaccharide hexyl glycoside and the Leb and H-1 antigens aminohexyl glycosides to be used in ELISA experiments. We describe an improved preparation of the 6-O-benzyl-2,3,4-tri-O-acetyl-α-d-galactopyranosyl bromide in neutral conditions and demonstrate the importance of appropriately "matching" the reactivity of acceptors with that of glycosyl donors. Mono- and di-fucosylation of a disaccharide diol acceptor with per-benzylated thioethyl fucoside activated in situ with bromine and under halide ion catalysis is described and our results are compared to literature reports. We observed that our fucosylation reactions required higher equivalents of fucosyl donor and extended reaction times than previously reported. We propose that the protecting groups on the galactosyl unit led to a reduced reactivity of the acceptor. The protected intermediates were converted to 6-azido hexyl glycosides and submitted to dissolving metal conditions to give 6-aminohexyl glycosides. We also prepared the n-hexyl tetrasaccharide glycoside Leb that will be used as a soluble antigen in competitive ELISA experiments. [ABSTRACT FROM AUTHOR]

Proteus mirabilis is a pathogenic Gram‐negative bacterium that causes several kinds of infections in human beings. Herein, we present the first total synthesis of the O‐antigen tetrasaccharide repeating unit of P. mirabilis OC (CCUG 10702) serogroup O75 with an aminoethyl linker appended at the reducing end. The tetrasaccharide comprising D‐glucosamine, L‐rhamnose, D‐galactose and D‐galactosamine with a key (1→4)‐α‐glycosidic linkage between D‐galactose and L‐rhamnose was assembled by three stepwise [1+1+1+1], [1+2+1] and [2+2] assembly approaches and one one‐pot [1+2+1] assembly. The respective routes provided the tetrasaccharide in yields of 23 %, 18 %, 20 %, and 26 % from suitably protected monosaccharide building blocks. [ABSTRACT FROM AUTHOR]

[Display omitted] • Covalent inhibitors are gaining renewed attention in drug discovery, however, there are very few examples of antifungal covalent drugs. • Aromatic glycoconjugates (AGCs), some with reactive functional groups such as acryloyl and vinyl sulfone moieties, were synthesised. • Their fungicidal efficacy against fungal pathogens of the Candida spp was investigated. • The ability of active galactose derivatives to crosslink nucleophilic side chains was assessed in model reactions. Covalent drugs are becoming increasingly attractive in drug discovery, as they can enhance potency and selectivity for their molecular targets. Covalent inhibitors have been investigated for several therapeutic applications, including anti-cancer and anti-infection agents. However, there are only a few examples of covalent inhibitors targeting fungal pathogens. We have previously reported aromatic glycoconjugates (AGCs) capable of inhibiting the adhesion of Candida albicans to buccal epithelial cells. In this work, we synthesize novel derivatives of the AGCs to which we have added reactive functional groups, such as acryloyl and vinyl sulfones, and investigated their antifungal efficacy against Candida spp. Although the compounds were ineffective at clinically relevant concentrations, we found that some of the galactose derivatives featuring reactive groups were amongst the most active, so their ability to crosslink nucleophilic side chains was assessed in model reactions. [ABSTRACT FROM AUTHOR]

Cucumber is one of the most widely cultivated greenhouse vegetables, and its quality and yield are threatened by drought stress. Studies have shown that carbon dioxide concentration ([CO2]) enrichment can alleviate drought stress in cucumber seedlings; however the mechanism of this [CO2] enrichment effect on root drought stress is not clear. In this study, the effects of different drought stresses (simulated with 0, 5% and 10% PEG 6000, i.e., no, moderate, and severe drought stress) and [CO2] (400 μmol·mol−1 and 800 ± 40 μmol·mol−1) on the cucumber seedling root proteome were analyzed using the tandem mass tag (TMT) quantitative proteomics method. The results showed that after [CO2] enrichment, 346 differentially accumulating proteins (DAPs) were found only under moderate drought stress, 27 DAPs only under severe drought stress, and 34 DAPs under both moderate and severe drought stress. [CO2] enrichment promoted energy metabolism, amino acid metabolism, and secondary metabolism, induced the expression of proteins related to root cell wall and cytoskeleton metabolism, effectively maintained the balance of protein processing and degradation, and enhanced the cell wall regulation ability. However, the extent to which [CO2] enrichment alleviated drought stress in cucumber seedling roots was limited under severe drought stress, which may be due to excessive damage to the seedlings. [ABSTRACT FROM AUTHOR]

Duckweeds are fast-growing aquatic plants suitable for bioenergy due to fermentable-rich biomass with low lignin and unique cell wall. The plant cell wall is built from pathways of nucleotide sugar genes that culminate in cell wall synthesis and deposition. Therefore, understanding these pathways by mapping the genes involved and their expression would be necessary for developing tools to improve bioenergy production. In this work, the genes associated with the NDP-sugar pathway (de novo and salvage) were mapped and correlated to the chemical characterization of the giant duckweed (Spirodela polyrhiza) cell wall. This plant biomass has been characterized as having 3% starch, 49% soluble sugars, 40% cell wall, and 8% non-measured compounds. The cell walls are synthesized by the NDP-sugar pathway and represent a significant carbon sink. This sink results from the action of proteins encoded by 190 orthologs of the 38 targets of the NDP-sugar pathway, of which 49 are starch and sucrose-related, 54 pectins-related, 65 hemicellulose-related, and 23 cellulose-related. Chemical analysis of the cell wall revealed 49% pectins, 23% hemicellulose, and 10% cellulose. These carbohydrates can potentially provide biorefinery as adjuvants, cosmetics, food additives, stabilizers, gelling agents, and principally as biofuels. [ABSTRACT FROM AUTHOR]

A cationic gold(I)-catalyzed O-glycosylation method involving the use of glycosyl S-3-butynyl thiocarbonate donors has been developed. It was found that glycosyl S-3-butynyl thiocarbonates are orthogonal to regular phenyl thioglycoside donors. The utilization of this method was demonstrated in the synthesis of a trisaccharide. [ABSTRACT FROM AUTHOR]

• L352M alters donor and acceptor subsites, causing a domino effect in the active site. • R69 is confirmed as a key determinant of the transglycosylation/hydrolysis partition. • Active site flexibility contributes to the transglycosylation/hydrolysis equilibrium. • N216W leads to a hydrophobic platform for better acceptor binding. • A complex interplay of mutational effects procures better transglycosylase activity. The use of retaining glycoside hydrolases as synthetic tools for glycochemistry is highly topical and the focus of considerable research. However, due to the incomplete identification of the molecular determinants of the transglycosylation/hydrolysis partition (t/h), rational engineering of retaining glycoside hydrolases to create transglycosylases remains challenging. Therefore, to understand better the factors that underpin transglycosylation in a GH51 retaining α- l -arabinofuranosidase from Thermobacillus xylanilyticus, the investigation of this enzyme's active site was pursued. Specifically, the properties of two mutants, F26L and L352M, located in the vicinity of the active site are described, using kinetic and 3D structural analyses and molecular dynamics simulations. The results reveal that the presence of L352M in the context of a triple mutant (also containing R69H and N216W) generates changes both in the donor and acceptor subsites, the latter being the result of a domino-like effect. Overall, the mutant R69H-N216W-L352M displays excellent transglycosylation activity (70 % yield, 78 % transfer rate and reduced secondary hydrolysis of the product). In the course of this study, the central role played by the conserved R69 residue was also reaffirmed. The mutation R69H affects both the catalytic nucleophile and the acid/base, including their flexibility, and has a determinant effect on the t / h partition. Finally, the results reveal that increased loop flexibility in the acceptor subsites creates new interactions with the acceptor, in particular with a hydrophobic binding platform composed of N216W, W248 and W302. [ABSTRACT FROM AUTHOR]

β-Glucan phosphorylases are carbohydrate-active enzymes that catalyze the reversible degradation of β-linked glucose polymers, with outstanding potential for the biocatalytic bottom-up synthesis of β-glucans as major bioactive compounds. Their preference for sugar phosphates (rather than nucleotide sugars) as donor substrates further underlines their significance for the carbohydrate industry. Presently, they are classified in the glycoside hydrolase families 94, 149, and 161 (www.cazy.org). Since the discovery of β-1,3-oligoglucan phosphorylase in 1963, several other specificities have been reported that differ in linkage type and/or degree of polymerization. Here, we present an overview of the progress that has been made in our understanding of β-glucan and associated β-glucobiose phosphorylases, with a special focus on their application in the synthesis of carbohydrates and related molecules. Key points: • Discovery, characteristics, and applications of β-glucan phosphorylases. • β-Glucan phosphorylases in the production of functional carbohydrates. [ABSTRACT FROM AUTHOR]

Epimerization of sugar nucleotides is central to the structural diversification of monosaccharide building blocks for cellular biosynthesis. Epimerase applicability to carbohydrate synthesis can be limited, however, by the high degree of substrate specificity exhibited by most sugar nucleotide epimerases. Here, we discovered a promiscuous type of CDP-tyvelose 2-epimerase (TyvE)-like enzyme that promotes C-2 epimerization in all nucleotide (CDP, UDP, GDP, ADP, and TDP)-activated forms of d-glucose. This new epimerase, originating from Thermodesulfatator atlanticus, is a functional homodimer that contains one tightly bound NAD+/subunit and shows optimum activity at 70°C and pH 9.5. The enzyme exhibits a kcat with CDP-d-glucose of ∼1.0 min−1 (pH 7.5 and 60°C). To characterize the epimerase kinetically and probe its substrate specificity, we developed chemoenzymatic synthesis for CDP-d-mannose, CDP-6-deoxy-d-glucose, CDP-3-deoxy-d-glucose, and CDP-6-deoxy-d-xylo-hexopyranos-4-ulose. Attempts to obtain CDP-d-paratose and CDP-d-tyvelose were not successful. Using high-resolution carbohydrate analytics and in situ nuclear magnetic resonance (NMR) to monitor the enzymatic conversions (60°C and pH 7.5), we show that the CDP-d-mannose/CDP-d-glucose ratio at equilibrium is 0.67 (±0.1), determined from the kinetic Haldane relationship and directly from the reaction. We further show that deoxygenation at sugar C-6 enhances the enzyme activity 5-fold compared to CDP-d-glucose, whereas deoxygenation at C-3 renders the substrate inactive. Phylogenetic analysis places the T. atlanticus epimerase into a distinct subgroup within the sugar nucleotide epimerase family of SDRs (short-chain dehydrogenases/reductases), for which the current study now provides functional context. Collectively, our results expand an emerging toolbox of epimerase-catalyzed reactions for sugar nucleotide synthesis. IMPORTANCE Epimerases of the sugar nucleotide-modifying class of enzymes have attracted considerable interest in carbohydrate (bio)chemistry for the mechanistic challenges and the opportunities for synthesis involved in the reactions catalyzed. The discovery of new epimerases with an expanded scope of sugar nucleotide substrates used is important to promote mechanistic inquiry and can facilitate the development of new enzyme applications. Here, a CDP-tyvelose 2-epimerase-like enzyme from Thermodesulfatator atlanticus is shown to catalyze sugar C-2 epimerization in CDP-glucose and other nucleotide-activated forms of d-glucose. The reactions are new to nature in the context of enzymatic sugar nucleotide modification. The current study explores the substrate scope of the discovered C-2 epimerase and, based on modeling, suggests structure-function relationships that may be important for specificity and catalysis. [ABSTRACT FROM AUTHOR]

The (chemo-)enzymatic synthesis of oligosaccharides has been hampered by the lack of appropriate enzymatic tools with requisite regio- and stereo-specificities. Engineering of carbohydrate-active enzymes, in particular targeting the enzyme active site, has notably led to catalysts with altered regioselectivity of the glycosylation reaction thereby enabling to extend the repertoire of enzymes for carbohydrate synthesis. Using a collection of 22 mutants of ΔN123-GBD-CD2 branching sucrase, an enzyme from the Glycoside Hydrolase family 70, containing between one and three mutations in the active site, and a lightly protected chemically synthesized tetrasaccharide as an acceptor substrate, we showed that altered glycosylation product specificities could be achieved compared to the parental enzyme. Six mutants were selected for further characterization as they produce higher amounts of two favored pentasaccharides compared to the parental enzyme and/or new products. The produced pentasaccharides were shown to be of high interest as they are precursors of representative haptens of Shigella flexneri serotypes 3a, 4a and 4b. Furthermore, their synthesis was shown to be controlled by the mutations introduced in the active site, driving the glucosylation toward one extremity or the other of the tetrasaccharide acceptor. To identify the molecular determinants involved in the change of ΔN123-GBD-CD2 regioselectivity, extensive molecular dynamics simulations were carried out in combination with in-depth analyses of amino acid residue networks. Our findings help to understand the inter-relationships between the enzyme structure, conformational flexibility and activity. They also provide new insight to further engineer this class of enzymes for the synthesis of carbohydrate components of bacterial haptens. [ABSTRACT FROM AUTHOR]

[Display omitted] A 9-step synthetic route to a protected form of the C3-epimer of virenose from d -fucose is described. C3- epi -virenose is the carbohydrate unit of the bioactive polyketide elsamicin B and part of the carbohydrate unit of elsamicin A. The developed route enabled preparation of anomerically activated forms of this unique C6-deoxy sugar, including derivatives with 1-acetyl, 1-acetylthio, 1-trichloroacetimidate, 1-bromo, and 1-fluoro substituents. [ABSTRACT FROM AUTHOR]

Functionalized carbohydrates and especially functionalized C -glycosides are useful intermediates for the synthesis of complex carbohydrates of interest. In this paper, we describe the synthesis of C -azidopropylglucopyranosides and give a full account of their regioselective acylation and alkylation. Alkylation of these C -glucosyl compounds containing 1,2- trans -diol, namely 2- and 3-OH were first optimized with benzyl bromide. The reaction has then been extended to various electrophiles thus providing 3- O -substituted C -glucosyl compounds. These results are one of the first examples of regioselective alkylation with functionalized electrophiles on glycosyl compounds featuring a trans -vicinal diol. Furthermore, we describe some results obtained during regioselective deprotection of 4,6- O -benzylidene protecting group. This work opens the way to the synthesis of complex carbohydrate derivatives. Image 1 • Efficient synthesis of C -azidopropylglucopyranosides. • Regioselective alkylation of C -glucopyranosides. • Access to value-added C -glycosyl derivatives. [ABSTRACT FROM AUTHOR]

We recently developed a novel chiral N‐heterocyclic carbene (NHC) catalyzed dynamic kinetic enantioselective acylation (DKEA) and dynamic kinetic diastereoselective acylation (DKDA) of Achmatowicz rearrangement products to generate useful intermediates for the further synthesis of carbohydrates. In this update, we describe a divergent NHC catalytic strategy for the stereoselective preparation of all four isomers starting from a common racemic precursor. The present report provides easy access to diverse optically pure dihydropyranones. [ABSTRACT FROM AUTHOR]

Abstract Carbohydrates are structurally complex but functionally important biomolecules. Therefore, they have been challenging but attractive synthetic targets. While substantial progress has been made on advancing chemical glycosylation methods, incorporating enzymes into carbohydrate synthetic schemes has become increasingly practical as more carbohydrate biosynthetic and metabolic enzymes as well as their mutants with synthetic application are identified and expressed for preparative and large-scale synthesis. Chemoenzymatic strategies that integrate the flexibility of chemical derivatization with enzyme-catalyzed reactions have been extremely powerful. Briefly summarized here are our experiences on developing one-pot multienzyme (OPME) systems and representative chemoenzymatic strategies from others using glycosyltransferase-catalyzed reactions for synthesizing diverse structures of oligosaccharides, polysaccharides, and glycoconjugates. These strategies allow the synthesis of complex carbohydrates including those containing naturally occurring carbohydrate postglycosylational modifications (PGMs) and non-natural functional groups. By combining these srategies with facile purification schemes, synthetic access to the diverse space of carbohydrate structures can be automated and will not be limited to specialists. Graphical abstract Image 1 Highlights • Recent glycosyltransferase-dependent chemoenzymatic strategies are summarized. • One-pot multienzyme (OPME) glycosylation systems are highly efficient. • Enzymatically synthesized building blocks can be used for chemical glycosylation. • Identifying suitable enzymes and mutants is the key to success. • Strategies for regioselective glycosylation and facile purification are discussed. [ABSTRACT FROM AUTHOR]

The bleomycins (BLMs) are known antitumor antibiotics composed of the tumoricidal and tumor seeking domains. The peptide structure of BLMs is responsible for the cytotoxicity by selective oxidative cleavage of DNA (and RNA), while the tumor cell selectivity and internalization resides in the disaccharide moiety (i.e. BLM disaccharide). This has prompted researchers to utilize BLM disaccharide and its derivatives as constituents for the selective recognition of tumor cells, which may find further applications as new tumor imaging tools or drug delivery vehicles. In the present study a high yielding synthesis of an alkyne modified BLM disaccharide precursor that may be used as a useful agent for the click conjugation, its conversion to a 18F‐labeled radiotracer, and preliminary in vivo PET imaging studies of the tracer with breast cancer (MCF‐7) xenograft mouse models are described. An alkyne modified bleomycin disaccharide has been synthesized from diacetone‐α‐d‐glucose and converted to a 18F radiotracer. Preliminary in vivo‐PET imaging studies has been described. [ABSTRACT FROM AUTHOR]

Diabetes care during exercise frequently requires interruptions to activity and adds extra challenges particularly for young individuals with type 1 diabetes (T1D). This study investigated the use of a carbohydrate (CHO) intake algorithm based on continuous glucose monitoring (CGM) trends during physical activity. Children with T1D diagnosed for >1 year, ages 8-12 years, with a glycated hemoglobin of <10% were recruited into a randomized crossover study. They attended two similar mornings of fun-based physical activity and adhered to either a CHO intake algorithm based on CGM trends (intervention) or to standard exercise guidelines (consumption of 0.5 g CHO/kg/h when glucose <8 mmol/L) (control). Outcome measures included events such as exercise interruptions, CHO intake, and hypoglycemia events and percentage time spent in different sensor glucose ranges. Fourteen children completed the study. No episodes of significant hypoglycemia (sensor glucose level <3.0 mmol/L) occurred in either arm. Mean CHO intake was the same in both arms, 0.3 ± 0.2 g/kg/h. However, the intervention algorithm resulted in fewer CHO intake events per day: rate [95% confidence interval] 2.4 [1.6-2.3] versus 0.9 [0.4-1.5], P < 0.001, and exercise interruptions: 7.2 [5.9-8.8] versus 1.4 [0.8-2.1], P < 0.001, compared with control. There was no evidence of a difference in percentage time in range (3.9-10 mmol/L) and percentage time spent high between study arms. Both control and intervention protocols prevented significant hypoglycemia. Using a CHO intake algorithm based on CGM trends resulted in fewer CHO intake events and fewer interruptions to exercise. Use of this algorithm may reduce the burden of diabetes management with potential to facilitate activity in young people with T1D. [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]

Abstract A general and highly selective method for the synthesis of carbohydrate-derived ( Z )-vinyl halides and silanes is described. This reaction takes place through a β-elimination process of sugar-derived α-halomethylcarbinol acetates promoted by samarium diiodide. Starting materials have been easily prepared in two steps consisting in an initial addition of halomethyllithium compounds to the corresponding galactose-derived aldehyde, followed by acetylation. A mechanism that explains both the formation of ( Z )-vinyl derivatives and its selectivity is proposed. Finally, the synthetic usefulness of these compounds has been applied in cross-coupling reactions with ethynyl benzene towards the formation of selected enyne derivatives. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

We have described CsF-catalyzed trifluoromethylation of heteroaromatic aldehydes at room temperature to afford trifluoromethyl group containing alcohols in very good yields. Using catalytic amount of CsF (0.2 eq.) in toluene, trifluoromethylated products were achieved in good yields at rt. The substrate scope has been exemplified by a large number of substrates. As an application, iodo etherification/cyclization has also been demonstrated for the synthesis of trifluoromethyl pyrano[4,3- b ]quinoline from o-alkynyltrifluoro methyl alcohol, in very good yield. [ABSTRACT FROM AUTHOR]

Despite the important advances in chemical and chemoenzymatic synthesis of glycans, access to large quantities of complex natural glycans remains a major impediment to progress in Glycoscience. Here we report a large-scale preparation of N-glycans from a kilogram of commercial soy proteins using oxidative release of natural glycans (ORNG). The high mannose and paucimannose N-glycans were labeled with a fluorescent tag and purified by size exclusion and multidimensional preparative HPLC. Side products are identified and potential mechanisms for the oxidative release of natural N-glycans from glycoproteins are proposed. This study demonstrates the potential for using the ORNG approach as a complementary route to synthetic approaches for the preparation of multi-milligram quantities of biomedically relevant complex glycans. [ABSTRACT FROM AUTHOR]

The biomass production and changes in biochemical composition of a locally isolated microalga ( Chlorella sp.) were investigated in autotrophic, mixotrophic and heterotrophic conditions, using glucose or glycerol as carbon sources and municipal wastewater as the growth medium. Both standard methods and Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) analysis of data acquired by Fourier-transform IR (FTIR) spectrometry showed that autotrophic and mixotrophic conditions promoted carbohydrate accumulation, while heterotrophic conditions with glycerol resulted in the highest lipid content and lowest carbohydrate content. Heterotrophic conditions with glycerol as a carbon source also resulted in high oleic acid (18:1) contents and low linolenic acid (18:3) contents, and thus increasing biodiesel quality. The results also show the utility of MCR-ALS for analyzing changes in microalgal biochemical composition. [ABSTRACT FROM AUTHOR]

A microbioreactor immobilized with a synthase-type mutant enzyme, Endo-M-N175Q (glycosynthase) of endo-β- N -acetylglucosaminidase derived from Mucor hiemalis (Endo-M), was constructed and used for glycoconjugate synthesis. The transglycosylation was performed with a reaction mixture containing an oxazoline derivative of sialo complex-type glycoside (SG), which was prepared from a sialo complex-type glycopeptide SGP derived from hen egg yolk, as a glycosyl donor and N -Fmoc- N -acetylglucosaminyl- l -asparagine [Fmoc-Asn(GlcNAc)-OH] as an acceptor. The reaction mixture was injected into a glycosynthase microbioreactor at a constant flow rate. Highly efficient and nearly stoichiometric transglycosylation occurred in the microbioreactor, and the transglycosylation product was eluted from the other end of the reactor. The glycosynthase microbioreactor was stable and could be used repeatedly for a long time. [ABSTRACT FROM AUTHOR]

Advanced vibrational molecular spectroscopy has been developed as a rapid and non-destructive tool to reveal intrinsic molecular structure conformation of biological tissues. However, this technique has not been used to systematically study flaking induced structure changes at a molecular level. The objective of this study was to use vibrational molecular spectroscopy to reveal association between steam flaking induced CHO molecular structural changes in relation to grain CHO fractionation, predicted CHO biodegradation and biodigestion in ruminant system. The Attenuate Total Reflectance Fourier-transform Vibrational Molecular Spectroscopy (ATR-Ft/VMS) at SRP Key Lab of Molecular Structure and Molecular Nutrition, Ministry of Agriculture Strategic Research Chair Program (SRP, University of Saskatchewan) was applied in this study. The fractionation, predicted biodegradation and biodigestion were evaluated using the Cornell Net Carbohydrate Protein System. The results show that: (1) The steam flaking induced significant changes in CHO subfractions, CHO biodegradation and biodigestion in ruminant system. There were significant differences between non-processed (raw) and steam flaked grain corn ( P < .01); (2) The ATR-Ft/VMS molecular technique was able to detect the processing induced CHO molecular structure changes; (3) Induced CHO molecular structure spectral features are significantly correlated ( P < .05) to CHO subfractions, CHO biodegradation and biodigestion and could be applied to potentially predict CHO biodegradation ( R 2 = 0.87, RSD = 0.74, P < .01) and intestinal digestible undegraded CHO ( R 2 = 0.87, RSD = 0.24, P < .01). In summary, the processing induced molecular CHO structure changes in grain corn could be revealed by the ATR-Ft/VMS vibrational molecular spectroscopy. These molecular structure changes in grain were potentially associated with CHO biodegradation and biodigestion. [ABSTRACT FROM AUTHOR]

The wide use of carbohydrate-based compounds is the pharmaceutical, cosmetic, detergent and food industry has led to the development of efficient synthetic procedures to overcome many drawbacks of conventional synthetic methodologies such as protection/activation/deprotection steps. In this context, due to their high chemo-, regio- and stereoselectivity, enzymes offer very effective and sustainable possibilities, and thus, they are increasingly used in carbohydrate field. In addition, the combination of biocatalysis and the use of green solvents is becoming a real alternative, as many solvents provide interactions with enzymes improving their catalytic behaviour, and they both directly contribute to increase the processes sustainability. This review will provide recent examples of the enzymatic preparation of carbohydrates and glycoconjugates using a combination of hydrolases (lipase and glycosidases) and green solvents. [ABSTRACT FROM AUTHOR]

Ketosamines are an important class of glycoconjugates widely employed in clinical diagnostics and implicated in development of diabetic complications, intestinal infections, or advanced cancer, as well as in food organoleptic and nutritional value. We report on the first preparation and structural characterization of 1-amino-1-deoxy-L-sorbose (L-sorbosamine, L-SorNH2). The monosaccharide was synthesized from L-sorbose following a classic phenylosazone protocol. In aqueous solution, L-SorNH2 assumes an anomeric equilibrium consisting of 89.3% α-pyranose, 3.7% β-pyranose, 3.8% α-furanose, 2.4% β-furanose, and 0.9% acyclic keto tautomer. The α-pyranose anomer in crystalline L-SorNH2 × HCl adopts the 2C5 chair conformation, with bond lengths and valence angles comparing well with related sorbopyranose structures. All hydroxyl oxygen atoms, the ammonium group and chloride ion are involved in an extensive hydrogen bonding network which is formed by infinite chains with fused antidromic R76(14), R54(10), and R43(8) cycles. The Hirshfeld surface analysis suggests a significant contribution of the non-polar intermolecular contacts to the crystal structure, as well. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium spp.) is an imperative economic crop of the globe due to its natural textile fiber. Molecular mechanisms of fiber development have been greatly revealed in allotetraploid cotton but remained unexplored in Gossypium herbaceum. G. herbaceum can withstand the rigors of nature like drought and pests but produce coarse lint. This undesirable characteristic strongly needs the knowledge of fiber development at molecular basis. The present study reported the transcriptome sequence of the developing fiber of G. herbaceum on pyrosequencing and its analysis. About 1.38 million raw and 1.12 million quality trimmed reads were obtained followed by de novo assembly-generated 20,125 unigenes containing 14,882 coding sequences (CDs). BLASTx-based test of homology indicated that A1-derived transcripts shared a high similarity with Gossypium arboreum (A2). Functional annotation of the CDs using the UniProt categorized them into biological processes, cellular components, and molecular function, COG classification showed that a large number of CDs have significant homology in COG database (6215 CDs), and mapping of CDs with Kyoto Encyclopedia of Genes and Genomes (KEGG) database generated 200 pathways ultimately showing predominant engagement in the fiber development process. Transcription factors were predicted by comparison with Plant Transcription Factor Database, and their differential expression between stages exposed their important regulatory role in fiber development. Differential expression analysis based on reads per kilobase of transcript per million mapped reads (RPKM) value revealed activities of specific gene related to carbohydrate and lipid synthesis, carbon metabolism, energy metabolism, signal transduction, etc., at four stages of fiber development, and was validated by qPCR. Overall, this study will help as a valuable foundation for diploid cotton fiber improvement. [ABSTRACT FROM AUTHOR]

A concise synthesis of C-furanosides has been achieved, starting from unprotected D-xylose and D-arabinose. Both sugars reacted with hydroxylamine 6 to give the respective nitrones. These underwent in-situ intramolecular 1,3-dipolar cycloaddition reactions to give, in each case, a pair of diastereomeric derivatives of 7-oxa-1-aza-bicyclo[2.2.1]heptane 7 and 8. The ratio of chromatographically separable diastereoisomers could be changed by carrying out the reaction in the presence of weak Lewis acid. Both D-xylose-derived stereoiso-mers 7a and 8a were converted into D-erythro-C-furanosides by tosylation or mesylation followed by catalytic hydrogenolysis. On the other hand, the formation of D-threo-C-furanosides from D-arabinose derivatives 7b and 8b under similar conditions was accompanied by the formation of minor amounts of polyhydroxyquinolizidines as a result of competitive N-alkylation. The polyhydroxyquinolizidine side-products were useful for the assignment of the configuration of the new compounds. [ABSTRACT FROM AUTHOR]

Laforin catalyses glycogen dephosphorylation. Mutations in its gene result in Lafora disease, a fatal progressive myoclonus epilepsy, the hallmark being water‐insoluble, hyperphosphorylated carbohydrate inclusions called Lafora bodies. Human laforin consists of an N‐terminal carbohydrate‐binding module (CBM) from family CBM20 and a C‐terminal dual‐specificity phosphatase domain. Laforin is conserved in all vertebrates, some basal metazoans and a small group of protozoans. The present in silico study defines the evolutionary relationships among the CBM20s of laforin with an emphasis on newly identified laforin orthologues. The study reveals putative laforin orthologues in Trichinella, a parasitic nematode, and identifies two sequence inserts in the CBM20 of laforin from parasitic coccidia. Finally, we identify that the putative laforin orthologues from some protozoa and algae possess more than one CBM20. [ABSTRACT FROM AUTHOR]

The ability to detect the undeclared addition of a juice of lesser economic value to one of higher value (juice-to-juice debasing) is a particular concern between apple and pear juices due to similarities in their major carbohydrate/polyol profiles. Fingerprint compounds for the detection of this type of adulteration were identified in both commercial apple and pear juices by HPLC-PDA, were isolated chromatographically, and structurally identified by LC-MS/MS. The apple juice fingerprint was identified as 4- O - p -coumarylquinic acid and two pear compounds as isorhamnetin-3- O -rutinoside and abscisic acid. Additionally, the HPLC-PDA profile of pear juices in combination with pear fingerprint compounds including arbutin could be used to identify samples originating from China versus those from other geographical locations. [ABSTRACT FROM AUTHOR]

Bacillus circulans Jordan 32352 was isolated from decaying organic matter in the New Jersey soil in the early 1930s. This soil-dwelling bacterium produced an enzyme capable of degrading the type 3 capsular polysaccharide (Pn3P) of Streptococcus pneumoniae (Spn). Early reports of this enzyme, Pn3Pase, demonstrated its inducibility by, and specificity for Pn3P. We set out to identify and clone this enzyme for its recombinant expression and characterization. We first sequenced the genome of this bacterial species, and reclassified the Pn3Pase producing bacterium as Paenibacillus species 32352. We identified the putative protein of Pn3Pase through mass spectrometry-based proteomics and cloned the gene for recombinant expression. We then characterized the oligosaccharide products generated upon the enzymatic depolymerization of Pn3P. Sequence analysis suggests that this glycoside hydrolase belongs to a new carbohydrate-active enzyme GH family. To our knowledge, this is the only enzyme to demonstrate Pn3P depolymerization activity. [ABSTRACT FROM AUTHOR]

CAZypedia was initiated in 2007 to create a comprehensive, living encyclopedia of the carbohydrateactive enzymes (CAZymes) and associated carbohydrate-binding modules involved in the synthesis, modification and degradation of complex carbohydrates. CAZypedia is closely connected with the actively curated CAZy database, which provides a sequence-based foundation for the biochemical, mechanistic and structural characterization of these diverse proteins. Now celebrating its 10th anniversary online, CAZypedia is a successful example of dynamic, community-driven and expert-based biocuration. [ABSTRACT FROM AUTHOR]

The current study evaluates and compares the stability of anaerobic digestion of Brewery Spent Grains (BSG) with and without addition of nutrients. Based on the composition of the BSG two levels of nutrients addition were defined. Control reactor, without addition of nutrients, showed signs of instability after 3 months of operation and collapsed. On the contrary, supplemented reactors led to a COD removal rate of 60% and a methane production of 280 NL CH 4 .kg −1 VS added . According to these results, it was possible to define an additive solution adapted to BSG degradation. [ABSTRACT FROM AUTHOR]

DC-SIGN is a receptor protruded from the membrane of immature dendritic cells (DCs) that participates in the activation of the immune response through the recognition of pathogen-associated molecular patterns (PAMPs). On the other hand, HIV exploits the interaction between high-mannose structures of its envelope glycoprotein gp120 and DC-SIGN to be transported towards and infect T-cells. DC-SIGN is involved in the recognition process in the form of a tetramer and the multiple exposition of carbohydrate recognition sites (CRSs) is amplified by the formation on the DCs membrane of patches of tetramers. DC-SIGN is then considered an interesting target to fight the virus and multivalent systems exposing multiple copies of ligating units for its CRSs are becoming valuable tools to reach this goal. We herein prepared four mannosylated calix[n]arenes ( 1a - d ) and tested them by Surface Plasmon Resonance (SPR) competition assays as inhibitors of the binding between DC-SIGN and a mannosylated BSA used as model of HIV gp120. IC 50 s in the μM range were found evidencing in particular for compound 1a that, although rather moderate, a multivalent effect is taking place in the inhibition activity of this cluster. A relative potency (rp/n) around 4, respect to the monovalent methyl α-mannoside and normalized for the number of monosaccharide on the scaffold, was observed. This result, compared with previously reported data relative to dendrimers with the same valency, indicates the calixarene as a promising scaffold to build efficient inhibitors for DC-SIGN and, in perspective, for HIV. [ABSTRACT FROM AUTHOR]

Background Mannoside phosphorylases are frequently found in bacteria and play an important role in carbohydrate processing. These enzymes catalyze the reversible conversion of β-1,2- or β-1,4-mannosides to mannose and mannose-1-phosphate in the presence of inorganic phosphate. Methods The biochemical parameters of this recombinantly expressed novel mannose phosphorylase were obtained. Furthermore purified reaction products were subjected to ESI- and MALDI-TOF mass spectrometry and detailed NMR analysis to verify this novel type of β-1,3-mannose linkage. Results We describe the first example of a phosphorylase specifically targeting β-1,3-mannoside linkages. In addition to mannose, this phosphorylase originating from the bacterium Zobellia galactanivorans could add β-1,3-linked mannose to various other monosaccharides and anomerically modified 5-bromo-4-chloro-3-indolyl-glycosides (X-sugars). Conclusions An unique bacterial phosphorylase specifically targeting β-1,3-mannoside linkages was discovered. General significance Functional extension of glycoside hydrolase family 130. [ABSTRACT FROM AUTHOR]

Alpine treelines are expected to move upslope with a warming climate. However, so far treelines have responded inconsistently and future shifts remain difficult to predict since many factors unrelated to temperature, such as biotic interactions, affect responses at the local scale. Especially during the earliest regeneration stages, trees can be strongly influenced by alpine vegetation via both competition and facilitation. We aimed to understand the relative importance of these two types of interaction in different vegetation structures for treeline regeneration dynamics. Effects of herbaceous alpine vegetation on seedling emergence and first-year performance were studied in a field experiment in the French Alps (2100 m a.s.l.) with five important European treeline tree species: Larix decidua, Picea abies, Pinus cembra, Pinus uncinata and Sorbus aucuparia. Total emergence and locally-germinated seedling survival were not affected, but for seedlings planted at two months of age, negative vegetation impacts dominated for all response parameters: first-year survival, growth and carbohydrate accumulation. However, in the winter half-year, evergreen tree seedlings increased carbohydrate reserves under the protection of senescent herbs. Also, responses of locally-germinated seedlings suggest facilitative vegetation effects in the first two months after emergence. Thus, the interaction switched between competition and facilitation according to ontogenetic stage and seasons. Still, the net outcome after one year was negative, but species differed in their susceptibilities. Because initial establishment is the first bottleneck determining whether treelines remain stable or move upslope, understanding establishment, including site-, life-stage and species-specific processes, is essential for understanding observed treeline spatial patterns and dynamics. When developing predictive models of treeline dynamics, all these 'local' aspects should be incorporated in addition to more global drivers like changes in temperature. [ABSTRACT FROM AUTHOR]

The emergence of multidrug resistance cell lines is one of the major obstacles in the success of cancer chemotherapeutic treatment. Therefore, it remains a big challenge the development of new and effective drugs to defeat cancer. The presence of nitrogen heterocycles in the architectural design of drugs has led to the discovery of new leading compounds. Herein, we report the synthesis, characterization and in vitro antiproliferative activity against six cancer cell lines of d -ribofuranoside derivatives bearing a 1,2,4-oxadiazolic ring, with the aim of developing new active compounds. Most of these derivatives exhibit significant antiproliferative activities in the micromolar range. Noteworthy, the most potent compound of the series showed better selectivity towards the more resistant colon cancer cell line WiDr. [ABSTRACT FROM AUTHOR]

Among other classes of biomolecules, carbohydrates and glycoconjugates are widely involved in numerous biological functions. In addition to addressing the related synthetic challenges, glycochemists have invested intense efforts in providing access to structures that can be used to study, activate, or inhibit these biological processes. Over the past few decades, aminooxylated carbohydrates have been found to be key building blocks for achieving these goals. This review provides the first in-depth overview covering several aspects related to the syntheses and applications of aminooxylated carbohydrates. After a brief introduction to oxime bonds and their relative stabilities compared to related CN functions, synthetic aspects of oxime ligation and methodologies for introducing the aminooxy functionality onto both glycofuranosyls and glycopyranosyls are described. The subsequent section focuses on biological applications involving aminooxylated carbohydrates as components for the construcion of diverse architectures. Mimetics of natural structures represent useful tools for better understanding the features that drive carbohydrate-receptor interaction, their biological output and they also represent interesting structures with improved stability and tunable properties. In the next section, multivalent structures such as glycoclusters and glycodendrimers obtained through oxime ligation are described in terms of synthetic design and their biological applications such as immunomodulators. The second-to-last section discusses miscellaneous applications of oxime-based glycoconjugates, such as enantioselective catalysis and glycosylated oligonucleotides, and conclusions and perspectives are provided in the last section. [ABSTRACT FROM AUTHOR]

This study provides a new insight into our understanding of yeast response to starvation conditions (sole acetate as carbon source) and applied polarization and offers important information about the role of the glyoxylate cycle in the carbohydrate synthesis and extracellular charge transfer processes in biofuel cells. The biosynthetic capabilities of yeast C. melibiosica 2491 and the up/down-regulation of the glyoxylate cycle are evaluated by modifying the cellular metabolism by feedback inhibition or carbohydrate presence and establishing the malate dehydrogenase activity and carbohydrate content together with the electric charge passed through bioelectrochemical system. 10 mM malate leads to a decrease of the produced quantity of electricity with ca. 55%. At the same time, 24-times lower intracellular malate dehydrogenase activity is established. At polarization conditions the glyoxylate pathway is up-regulated and huge amount of malate is intra-converted into oxaloacetate. The yeasts are able to synthesize carbohydrates from acetate and a part of them is used for the electricity generation. It is recognized that the enhanced charge transfer in acetate fed yeast-based biofuel cell is implemented by secreted endogenous mediator and changes in the cellular surface redox activity depending on the addition of carbohydrate in the medium. [ABSTRACT FROM AUTHOR]

A series of glucosyl esters surfactants were synthesized based on glucose molecule by enzymatic catalysis. It could reach the highest esterification yield of 83.4% at the optimal condition, molar ratio of D-glucose and fatty acyl amino acid as 3:2 using 11% (w/w) enzyme catalyst Lipozyme 435 as catalyst int-butanol at 40°C. The surface activities were studied, such as the critical micelle concentration (CMC), surface tension (γcmc), maximum excess concentration (Γmax), minimum surface area/molecule (Amin), and the adsorption efficiency (pC20); values of these were obtained by surface tension test. The results show that the longer the hydrophobic chain length, the lower the CMC and γcmc. The CMCs of novel glucosyl esters were between 4.4 and 1.5 mM. Further, the micellization physiochemical parameters, including Gibbs free energy of micellization (ΔG), standard enthalpy change (ΔH), and standard entropy change (ΔS) were calculated. It was indicated the micellization of glucosyl esters 9–16 was driven by entropy and deduced at different temperature. [ABSTRACT FROM AUTHOR]

Anomeric sugar lactones are important intermediates for the synthesis of C-glycosides, carbasugars and iminosugars. Herein we present a facile synthesis of anomeric sugar lactones via the DAIB/TEMPO oxidation of anomeric hydroxides. The reactions are very efficient providing the lactones in 2–4 h in almost quantitative yields. The reaction conditions tolerate several common protecting groups used in carbohydrate synthesis. The advantages of the present methodology over previously reported non-metal based methods have also been demonstrated through head to head comparisons. Finally, we have applied the reaction for the sequential conversion of anomeric thioglycosides to the lactones through sequential reactions with NBS followed by the oxidation with DAIB/TEMPO. [ABSTRACT FROM AUTHOR]

Hexacarbonyldicobalt-C-3-alkynyl-substituted glycal derivatives, when treated with BF3 ·OEt2 give rise to Nicholas-stabilized Ferrier cation intermediates (Ferrier-Nicholas cations) that react with alcohols or C-nucleophiles to give C-3-branched 2,3-unsaturated glycosides or C-glycosides, respectively. α- C-Glycosides were the sole compounds obtained when allyltrimethylsilane was used as the nucleophile. On the contrary, the reaction of C-3-alkynylglycals with heteroaryl or alcohol nucleophiles led to anomeric mixtures in which the β-anomers prevailed. The presence of the hexacarbonyldicobalt-C-3-alkynyl substituent seems to be of key importance in the stereoselectivity of these transformations, since the reaction of C-3-alkynylglycals - devoid of the hexacarbonyldicobalt moiety - showed a preferred α-stereoselectivity. Furthermore, a bis(indolyl) linear compound was obtained from the reaction of a hexacarbonyldicobalt-C-3-alkynylglycal with 2 equiv. of indole. [ABSTRACT FROM AUTHOR]

Galectin-3 modulates cell adhesion and signaling events by specific binding and cross-linking galactoside containing carbohydrate ligands. Proteolytic cleavage by metalloproteinases yields in vivo N-terminally truncated galectin-3 still bearing the carbohydrate recognition domain. Truncated galectin-3 has been demonstrated to act in vivo as a negative inhibitor of galectin-3 due to higher affinity for carbohydrate ligands. We here present our studies on a series of 12 human galectin-3 protein constructs. Truncated galectin-3 (Δ1-62 and Δ1-116) and fusions with SNAP-tag and/or yellow fluorescent protein (YFP) display altered binding efficiencies (ratio of maximum binding signal and apparent affinity constant Kd) to asialofetuin (ASF) in solid-phase enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR) binding assays. Galectin-3(Δ1-62) and full-length (native) galectin-3 have highest affinity to ASF in ELISA and SPR experiments, respectively, whereas galectin-3(Δ1-116) shows only weak binding. We demonstrate here for the first time that SNAP-tag and YFP fusions of galectin-3 and truncated galectin-3 proteins improve binding efficiencies to ASF. SNAP-tagged galectin-3, galectin-3(Δ1-62) and galectin-3(Δ1-116) are found with significant (3- to 6-fold) higher binding efficiencies in SPR when compared with native galectin-3. Fusion of truncated galectin-3 with YFP renders binding properties similar to native galectin-3, whereas in combination with SNAP-tag improved binding characteristics are obtained. Our results emphasize the importance of the N-terminal domain of human galectin-3 for ligand binding. Most importantly, in combination with fusion proteins suitable for the design of diagnostic and therapeutic tools binding properties can be beneficially tuned. The resulting novel protein tools may be advantageous for potential galectin-3 directed applications in tumor diagnostics and therapy. [ABSTRACT FROM AUTHOR]

An efficient methodology for the synthesis of aryl 1,2- cis -furanosidic linkages has been developed with 2-quinolinecarbonyl (Quin) group substituted furanose ethyl thioglycosides as glycosyl donors. The method permits a wide range of phenol acceptors to be used, thus resulting in the formation of structurally diverse phenol furanosides in good to excellent chemical yields with complete 1,2- cis anomeric selectivity. The synthetic utility of the approach has been demonstrated by concise preparation of the carbohydrate portion of antibiotic hygromycin A. [ABSTRACT FROM AUTHOR]

A highly efficient, green, and regioselective method for the benzylation of diols and polyols was developed. With the use of Ag2O (0.6 equiv.) and tetrabutylammonium bromide (0.1 equiv.) as co-catalysts, the iron(III)-catalyzed benzylation reaction proceeded to completion at 40 °C within 2-3 h and gave the products in high yields with high regioselectivities. A mechanism involving the principle of enhanced basicity of Ag2O by soft anions was proposed. [ABSTRACT FROM AUTHOR]

The glycoproteins of selected microbial pathogens often include highly modified carbohydrates such as 2,4-diacetamidobacillosamine (diNAcBac). These glycoconjugates are involved in host-cell interactions and may be associated with the virulence of medically significant Gram-negative bacteria. In light of genetic studies demonstrating the attenuated virulence of bacterial strains in which modified carbohydrate biosynthesis enzymes have been knocked out, we are developing small molecule inhibitors of selected enzymes as tools to evaluate whether such compounds modulate virulence. We performed fragment-based and high-throughput screens against an amino-sugar acetyltransferase enzyme, PglD, involved in biosynthesis of UDP-diNAcBac in Campylobacter jejuni. Herein we report optimization of the hits into potent small molecule inhibitors (IC50 < 300 nM). Biophysical characterization shows that the best inhibitors are competitive with acetyl coenzyme A and an X-ray cocrystal structure reveals that binding is biased toward occupation of the adenine subpocket of the AcCoA binding site by an aromatic ring. [ABSTRACT FROM AUTHOR]

The preparation of a glycosynthase, a catalytic nucleophile mutant of a glycosidase, is a well-established strategy for the effective synthesis of glycosidic linkages. However, glycosynthases derived from α-glycosidases can give poor yields of desired products because they require generally unstable β-glycosyl fluoride donors. Here, we investigate a transglycosylation catalyzed by a catalytic nucleophile mutant derived from a glycoside hydrolase family ( GH) 97 α-galactosidase, using more stable β-galactosyl azide and α-galactosyl fluoride donors. The mutant enzyme catalyzes the glycosynthase reaction using β-galactosyl azide and α-galactosyl transfer from α-galactosyl fluoride with assistance of external anions. Formate was more effective at restoring transfer activity than azide. Kinetic analysis suggests that poor transglycosylation in the presence of the azide is because of low activity of the ternary complex between enzyme, β-galactosyl azide and acceptor. A three-dimensional structure of the mutant enzyme in complex with the transglycosylation product, β-lactosyl α- d-galactoside, was solved to elucidate the ligand-binding aspects of the α-galactosidase. Subtle differences at the β→α loops 1, 2 and 3 of the catalytic TIM barrel of the α-galactosidase from those of a homologous GH97 α-glucoside hydrolase seem to be involved in substrate recognitions. In particular, the Trp residues in β→α loop 1 have separate roles. Trp312 of the α-galactosidase appears to exclude the equatorial hydroxy group at C4 of glucosides, whereas the corresponding Trp residue in the α-glucoside hydrolase makes a hydrogen bond with this hydroxy group. The mechanism of α-galactoside recognition is conserved among GH27, 31, 36 and 97 α-galactosidases. Database The atomic coordinates (code: ) have been deposited in the Protein Data Bank. [ABSTRACT FROM AUTHOR]

The keto group in the carbohydrate residue of diastereoisomeric Michael adducts of levoglucosenone and cyclohexanone is more reactive than that in the cyclohexanone fragment. The adducts have been converted to the corresponding ethylene, trimethylene, and dimethyl ketals, tosylhydrazones, oxiranes, and Wittig methylenation products with complete or high regioselectivity. [ABSTRACT FROM AUTHOR]

Sugars are the most stereochemically intricate family of biomolecules and present substantial challenges to anyone trying to understand their nomenclature, reactions or branched structures. Current crystallographic programs provide an abstraction layer allowing inexpert structural biologists to build complete protein or nucleic acid model components automatically either from scratch or with little manual intervention. This is, however, still not generally true for sugars. The need for carbohydrate-specific building and validation tools has been highlighted a number of times in the past, concomitantly with the introduction of a new generation of experimental methods that have been ramping up the production of protein-sugar complexes and glycoproteins for the past decade. While some incipient advances have been made to address these demands, correctly modelling and refining carbohydrates remains a challenge. This article will address many of the typical difficulties that a structural biologist may face when dealing with carbohydrates, with an emphasis on problem solving in the resolution range where X-ray crystallography and cryo-electron microscopy are expected to overlap in the next decade. [ABSTRACT FROM AUTHOR]

In this review, we discuss small-molecule, carbohydrate-based immunostimulants that target Toll-like receptor 4 (TLR-4) and cluster of differentiation 1D (CD1d) receptors. The design and use of these molecules in immunotherapy as well as results from their use in clinical trials are described. How these molecules work and their utilization as vaccine adjuvants are also discussed. Future applications and extensions for the use of these analogues as therapeutic agents will be outlined. [ABSTRACT FROM AUTHOR]