Nitrogen-containing Carbohydrate Research Articles

Polymeric carbohydrates utilization separates microbiomes into niches: insights into the diversity of microbial carbohydrate-active enzymes in the inner shelf of the Pearl River Estuary, China.

Polymeric carbohydrates are abundant and their recycling by microbes is a key process of the ocean carbon cycle. A deeper analysis of carbohydrate-active enzymes (CAZymes) can offer a window into the mechanisms of microbial communities to degrade carbohydrates in the ocean. In this study, metagenomic genes encoding microbial CAZymes and sugar transporter systems were predicted to assess the microbial glycan niches and functional potentials of glycan utilization in the inner shelf of the Pearl River Estuary (PRE). The CAZymes gene compositions were significantly different between in free-living (0.2-3 μm, FL) and particle-associated (>3 μm, PA) bacteria of the water column and between water and surface sediments, reflecting glycan niche separation on size fraction and selective degradation in depth. Proteobacteria and Bacteroidota had the highest abundance and glycan niche width of CAZymes genes, respectively. At the genus level, Alteromonas (Gammaproteobacteria) exhibited the greatest abundance and glycan niche width of CAZymes genes and were marked by a high abundance of periplasmic transporter protein TonB and members of the major facilitator superfamily (MFS). The increasing contribution of genes encoding CAZymes and transporters for Alteromonas in bottom water contrasted to surface water and their metabolism are tightly related with particulate carbohydrates (pectin, alginate, starch, lignin-cellulose, chitin, and peptidoglycan) rather than on the utilization of ambient-water DOC. Candidatus Pelagibacter (Alphaproteobacteria) had a narrow glycan niche and was primarily preferred for nitrogen-containing carbohydrates, while their abundant sugar ABC (ATP binding cassette) transporter supported the scavenging mode for carbohydrate assimilation. Planctomycetota, Verrucomicrobiota, and Bacteroidota had similar potential glycan niches in the consumption of the main component of transparent exopolymer particles (sulfated fucose and rhamnose containing polysaccharide and sulfated-N-glycan), developing considerable niche overlap among these taxa. The most abundant CAZymes and transporter genes as well as the widest glycan niche in the abundant bacterial taxa implied their potential key roles on the organic carbon utilization, and the high degree of glycan niches separation and polysaccharide composition importantly influenced bacterial communities in the coastal waters of PRE. These findings expand the current understanding of the organic carbon biotransformation, underlying the size-fractionated glycan niche separation near the estuarine system.

Macroscopic-scale synthesis of nitrogen-doped carbon nanofiber aerogels by template-directed hydrothermal carbonization of nitrogen-containing carbohydrates

Doping heteroatoms into carbon nanomaterials will greatly enhance their physiochemical properties, however, it is still challenging to prepare doped nanocarbons in large-scale by economical ways for industrial applications. Here, we report the macroscopic-scale synthesis of a new class of nitrogen-doped carbonaceous nanofibers (N-CNFs) aerogels with diameter from tens to hundreds nanometers by a template-directed hydrothermal carbonization (HTC) process, where ultrathin tellurium nanowires (TeNWs) as templates and nitrogen-containing carbohydrates as carbon sources. High-temperature treatment and CO2 activation of the N-CNFs endow them with high conductivity and porosity, resulting in outstanding performances as electrode materials for electrocatalysts and supercapacitors.

Surface Modification of CNTs with N-Doped Carbon: An Effective Way of Enhancing Their Performance in Supercapacitors

Carbon nanotubes have been successfully coated with a N-doped carbon layer via hydrothermal carbonization in the presence of a nitrogen-containing carbohydrate, i.e., glucosamine hydrochloride. By controlling the amount of glucosamine added, it was possible to tune the N content of the composites N-doped carbon/CNT between 1.8–2.5 wt %. The prepared composites exhibited superior supercapacitor performance in comparison to bare CNTs even though they possess lower textural properties. Thus, a 2- to 4-fold increase in specific capacitance per surface area was registered at low current densities and sweep rates and a 2-fold increase in energy density, while keeping the power density. Besides, the composites possess superb long-term stability, losing only 4–6% of specific capacitance after 10,000 cycles at 10 A g–1.

Sustainable nitrogen-doped carbon latexes with high electrical and thermal conductivity

Nitrogen-doped carbon particles were produced using the hydrothermal carbonization of a nitrogen-containing carbohydrate, namely glucosamine, under mild temperature conditions (180 °C) followed by further calcination under a stream of inert gas at 750 °C. The resulting materials contain significant amounts of nitrogen doping within their structure, mainly as quaternary N involved in an aromatized/graphitized carbon structure according to X-ray photoelectron spectroscopy. This nitrogen-doped material was dispersed with nanolatexes having a high affinity for carbon. The resulting hybrid dispersions could be conveniently cast into dense and stable films for thermal and electrical conductivity measurements. The conductivities were commensurate with technical carbon nanotube latex-based films. A morphological analysis of the dispersing mechanism suggests that the potential for high performance materials realized in this contribution is very competitive, but still far from being fully exploited.

Sustainable nitrogen-doped carbonaceous materials from biomass derivatives

Nitrogen-doped carbons were produced using hydrothermal carbonization of nitrogen-containing carbohydrates under mild temperature (180 °C). The resulting materials contain significant amounts of nitrogen and display a high degree of aromatization. The nitrogen contents are also retained after further calcination at higher temperatures. All the resulting materials have been thoroughly characterized using X-ray photoelectron spectroscopy, solid state 15N and 13C-nuclear magnetic resonance, elemental chemical analysis, nitrogen adsorption, scanning and transmission electron microscopy. The nitrogen-doped materials proved to have superior performance with respect to their nitrogen-free counterparts in terms of electrical conductivity.

Dynamics of Hyaluronan Oligosaccharides Revealed by 15N Relaxation

Complex carbohydrates are considered to be flexible biomolecules, yet few experimental techniques are available to characterize their dynamics. In this study, we investigate the potential of 15N relaxation to probe the dynamics of hyaluronan oligosaccharides by adapting approaches previously applied to proteins. Unlike the 13C nucleus, 15N provides considerably enhanced spectral resolution, allowing position-specific information to be measured even in the middle of oligomers as large as decasaccharides. Moreover, isotopic incorporation maintains the 1H-15N group as an isolated spin-pair, allowing relaxation experiments to be performed and interpreted at low concentrations. A methodology is described for calculating the Lipari and Szabo model-free parameters at specific positions in hyaluronan oligomers and is used to produce a dynamic representation for the hexasaccharide. In this model, the glycosidic linkages and acetamido rotamer were determined to deviate by 18 degrees and 24 degrees from their mean positions, respectively. This approach allows the dynamic structural characterization of hyaluronan and other nitrogen-containing carbohydrates. The resultant models provide crucial insights into the physical properties and biology of these flexible molecules, which are at present poorly understood.

Use of 15N-NMR to resolve molecular details in isotopically-enriched carbohydrates: sequence-specific observations in hyaluronan oligomers up to decasaccharides.

The glycosaminoglycan hyaluronan is a vital structural component of extracellular matrices with diverse biological functions, a molecular understanding of which requires a detailed description of secondary and tertiary solution structures. Various models of these structures have been proposed on the basis of 1H and 13C natural-abundance nuclear magnetic resonance (NMR) experiments, but resonance overlap limits further progress with these techniques. We have therefore produced 15N- and 13C- isotopically-labeled hyaluronan oligosaccharides and applied triple-resonance and 3D experiments to overcome this restriction. Spectra recorded on oligosaccharides (of lengths 4, 6, 8, 10, and 12 sugar rings), reveal that the 15N nucleus allows resolution of the amide groups in a decamer at high magnetic field, whereas 13C natural-abundance NMR can only resolve internal groups up to hexamers. Complete 13N sequence- specific assignments of these oligosaccharides indicate that the chemical shift dispersion can be explained by end-effects, which are seen even in the middle of octamers. Triple- resonance and 15N-edited 3D experiments, among the first of their kind in oligosaccharides, have been used to achieve resolution of ring 1H and 13C nuclei where not possible previously. The subtle chemical shift perturbations resolved suggest that different conformations and dynamics occur at the ends, which may contribute to the range of biological activities displayed by varying lengths of hyaluronan. 15N-NMR in carbohydrates has not received much attention before, however, this study demonstrates it has clear advantages for achieving resolution and assessing dynamic motion. These conclusions are likely to be applicable to the study of the structure and dynamics of other nitrogen-containing carbohydrates.

Aldolase-catalyzed C-C bond formation for stereoselective synthesis of nitrogen-containing carbohydrates

Rabbit muscle aldolase was found to catalyze stereoselective aldol addition of dihydroxyacetone phosphate (1) to 3-azido-2-hydroxypropana(2 ). The ketose 1-phosphates were isolated as barium salts, 4a/4b, and hydrolyzed with acid phosphatase. The mixture of 6-azido-6-deoxy-D-fructose(5) and 6-azido-6-deoxy-L-sorbose thus obtained was separated by anion-exchange chromatography. Reductive amination of 5 and 6 yielded, respectively, 1-deoxymannojirimycin (7) and 1-deoxynojirimycin (8), with high diastereoselectivity (>98:2). Analogous aldol addition of 1 to 3-azido-2-hydroxybutanal( 9)( E:Z = 92:8) afforded a mixture of the 6-azido-6,7-dideoxyheptuloses 12 and 13, which contained 88% of 6-azido-6,7-dideoxy-D-altro-heptulose(13 ). After anion-exchange chromatography, 13 was isolated as a 18:82 mixture of the β/α anomers. Reductive amination of pure 13 gave a mixture of 2,6,7-trideoxy-2,6-imino-D-glycero-D-manno and D-gluco-heptitol (14 and 15) (3:2 molar ratio), which likewise was separated by anion-exchange chromatography. If a mixture of 12 and 13 was hydrogenated under identical conditions, 2,6,7-trideoxy-2,6-imino-L-glycero-L-gulo-heptitol(16) could be isolated besides 14 and 15.

Nitrogen-containing carbohydrate derivatives. Part XXXII. Further studies on the ring-opening of epimino-sugars

Study of the ring-opening reactions of derivatives of methyl 4,6-O-benzylidene-2,3-dideoxy-2,3-epimino-α-D-allosides with azide ion has shown that these are ‘normal’(i.e. major diaxal opening) and not ‘abnormal’(i.e., major diequatorial opening) as previously reported. Some ring-opening reactions of the corresponding manosides are also reported.

Nitrogen-containing carbohydrate derivatives : Part XXVIII. Reaction of azido sugars with hydrazine and methylhydrazine

Several azido derivatives of aldosides, having tosyloxy, hydroxy, and deoxy neighbouring-groups, have been treated with hydrazine, with its hydrate, and with methylhydrazine. In general, complex mixtures of products resulted, and it is postulated that these were formed by simple reduction of the azido group to amine, and by decomposition of an intermediate di-imide derivative which gave olefins or deoxy compounds.

Nitrogen-containing carbohydrate derivatives. : Part VI. Synthesis and circular dichroism of 1,2-dideoxy-1-nitro alcohols

Nitrogen-containing carbohydrate derivatives. : Part VI. Synthesis and circular dichroism of 1,2-dideoxy-1-nitro alcohols

Nitrogen-containing carbohydrate derivatives. Part XXVII. Synthesis and reactions of 3-cyano-3-deoxy-glycose derivatives

Treatment of sugar oxirans with hydrogen cyanide–triethylaluminium in ether has been shown to be a useful method for the synthesis of cyano-deoxy-glycoses. Reactions of such compounds have been studied, in particular epimerisation at the cyanide-bearing centre, and formation of cyano-olefin derivatives.

Nitrogen-containing carbohydrate derivatives : Part XXVI. Periodate oxidation of methylated derivatives of amino sugars

Studies have been made of the periodate oxidation of carbohydrate derivatives containing the -CH(OH)-CH(NHMe)- and -CH(OH)-CH(NMe 2)- groupings, and having an eq,eq and ax,ax arrangement in each case. In the dimethylamino system, each compound gave the N-oxide, whereas the methylamino systems followed an oxidation pattern similar to that of the analogous -CH(OH)-CH(NH 2)- system studied in earlier work. Oxidation of compounds containing the -CH(OMe)-CN(NH 2)- grouping occured very slowly in a non-Malapradian fashion.

Nitrogen-containing carbohydrate derivatives : Part XXI. Periodate oxidation of methyl amino-4,6- O-benzylidene-deoxy-α- d-glycosides having the allo, manno, and gluco configurations

A study has been made of the periodate oxidation of methyl amino-4,6- O-benzylidene-deoxy-α- d-glycosides in the allo, gluco, and manno series. The results are compared with those for the oxidation of the corresponding diols and with those for cuprammonium complexing.

Nitrogen-containing carbohydrate derivatives : Part V. Synthesis and configurational determination of carbohydrate c-nitro alcohols by optical rotatory dispersion and circular dichroism

An epimeric pair 2-acetamido-1,2-dideoxy-1-nitro- D- glycero- D- talo-heptitol and 2-acetamido-1,2-dideoxy-1-nitro- D- glycero- D- galacto-heptitol, was synthesized from D-mannose. The absolute configuration at C-2 was based on the rules relating the signs of the Cotton effect of the o.r.d. curves and the c.d. maxima to the configuration at C-2 of the carbohydrate C-nitro alcohols. This assignment was confirmed by chemical degradation of 2-acetamido-1,2-dideoxy-1-nitro- D- glycero- D- talo-heptitol to D-serine. Another epimeric pair, 2-acetamido-1,2-dideoxy-1-nitro- D- glycero- L- manno-heptitol and 2-acetamido-1,2-dideoxy-1-nitro- D- glycero- L- gluco-heptitol, was synthesized, and the configurations at C-2, determined by optical methods, agreed with those established by chemical methods.

Nitrogen-containing carbohydrate derivatives : Part XVIII. Methyl 4,6- O-benzylidene-3-deoxy-3-methylazo-α- d-glucoside

Nitrogen-containing carbohydrate derivatives : Part XVIII. Methyl 4,6- O-benzylidene-3-deoxy-3-methylazo-α- d-glucoside

Nitrogen-containing carbohydrate derivatives : Part XV. The reaction of hydrazine with azido sugars

The reaction of a number of azido sugars with hydrazine has been studied. Vicinal azido-hydroxyl compounds gave the appropriate amino-alcohol, trans (ax-ax) and cis (ax-eq) azido-sulphonates both gave the corresponding olefin; trans (eq-eq) azido-sulphonates gave deoxy-sulphonates in which the HCN 3 group had been reduced to CH 2. Possible mechanisms are discussed.

Nitrogen-containing carbohydrate derivatives. Part XVI. Re-investigation of the ‘mutarotation’ of 3,4,5,6-tetra-O-benzoyl-D-glucose phenylhydrazone

The so-called ‘mutarotation’ of the title compound, previously assigned to phenylhydrazone–phenylazo-tautomerism, has been shown to be due to formation of a phenylazo-hydroperoxide.

Nitrogen-containing carbohydrate derivatives : Part XII. Reaction of epimino sugars with nitrous acid

Nitrogen-containing carbohydrate derivatives : Part XII. Reaction of epimino sugars with nitrous acid

Nitrogen-containing carbohydrate derivatives. Part X. Rearrangement of methyl 4,6-O-benzylidene-3-deoxy-3-phenylazo-aldohexopyranosides with alkali: a route to hexosid-3-uloses

The opening of the epoxide ring in methyl 2,3-anhydro-4,6-O-benzylidene-α-D-mannoside with phenylhydrazine, followed by oxidation of the product, has given methyl 4,6-O-benzylidene-3-deoxy-3-phenylazo-α-D-altroside. This compound and the α-gluco- and β-galacto-analogues have been rearranged by base to the corresponding 3-phenylhydrazones, which in turn have been converted into the parent hexosid-3-uloses, thus providing a new route to these compounds.