Carbon-13 Nuclear Magnetic Resonance Data for Oligosaccharides. Advances in Carbohydrate Chemistry and Biochemistry Volume 42. Elsevier; 1984. pp. 193-225. [DOI: 10.1016/s0065-2318(08)60125-0]

Immunologically active O6-branched (1-->3)-beta-glucan from the lichen Thamnolia vermicularis var. subuliformis

A lentinan-type gel-forming beta-glucan, Ths-2, has been isolated in about 1.5% yield from the alkali extract of the lichen Thamnolia vermicularis var. subuliformis, using ethanol fractionation, dialysis and gel filtration. The mean Mr of Ths-2 was determined by GP-HPLC to be 67 kD, and the optical rotation was measured to be -14 degrees. The structure of Ths-2 was further elucidated by methylation analysis by GC-MS, 1H- and 13C-NMR spectroscopy and selective enzymatic hydrolysis with exo-(1 --> 3)-beta-D-glucanase followed by analysis of oligosaccharides by HPAEC-PAD. Ths-2 was found to be consisting of a (1 --> 3)-beta-D-glucopyranosyl main chain with branches of a (1 --> 6) linked glucopyranosyl unit on every third unit of the main chain. Similar polysaccharide structures have been described from fungi, but this is the first report of a lentinan-type (1 --> 3)-beta-D-glucan from a lichen species. The immunomodulating activity of Ths-2 was tested in an in vitro anti-complementary assay, and proved to be strongly active.

Synthesis and antiviral evaluation of some new glycosylthioureas containing a quinazolinone nucleus

A new synthesis of glycosylthioureas containing a quinazolinone nucleus is described utilizing per-O-acetylglycopyranosylisothiocyanates and several aminoquinazolinones as starting compounds. Structural proofs of these compounds are provided from elemental analyses, IR, 1H and 13C NMR spectra and mass spectra. The biological activity of these compounds has been studied.

Fungal cell-wall galactomannans isolated from Geotrichum spp. and their teleomorphs, Dipodascus and Galactomyces

The alkali-extracted water-soluble galactomannan F1SS isolated from the cell wall of two species each of Geotrichum, Galactomyces, and Dipodascus have been studied by methylation analysis and NMR spectroscopy, and their structure is established as the following: [carbohydrate structure: see text]

Structural elucidation of the EPS of slime producing Brevundimonas vesicularis sp. isolated from a paper machine

The slime forming bacteria Brevundimonas vesicularis sp. was isolated from a paper mill and its EPS was produced on laboratory scale. After production, the exopolysaccharide (EPS) was purified and analysed for its purity and homogeneity, HPSEC revealed one distinct population with a molecular mass of more than 2,000 kDa. The protein content was around 9 w/w%. The sample was analysed to determine its chemical structure. The EPS was found to consist of rhamnose, glucose, galacturonic acid and glucuronic acid. Due to the presence of uronic acids the molar ratio between the four sugars found varies from 3:5:2:4 by sugar composition analyses after methanolysis to 1:1:1:1 found by NMR. A repeating unit with a molecular mass of 678 Da was confirmed by MALDI-TOF mass spectrometry after mild acid treatment. 13C and 1H hetero- and homonuclear 2D NMR spectroscopy of the native and partial hydrolysed EPS revealed a repeating unit, no non-sugar substituents were present.

Structure of the arabinogalactan from gum tragacanth (Astralagus gummifer)

The polysaccharide obtained by ethanol precipitation from an aqueous solution of gum tragacanth contained arabinogalactan and tragacanthic acid, as well as starch ( approximately 0.6%). GC-MS, NMR, and ESI-MS analyses showed the structure of the arabinogalactan to be even more complex than previously determined, with core structures containing Arap, beta-Araf, and alpha-Galp units, as well as known terminal, and 2-O- and 3-O-substituted alpha-Araf units. Analysis was aided by examination of free, reducing oligosaccharides present in the gum. In addition to maltose, maltotriose, maltotetraose, and maltopentaose, the following were characterized: mixed alpha-Araf (1-->2)-alpha-Araf-(1-->4)-Ara and alpha-Araf-(1-->2)-alpha-Araf-(1-->5)-Ara, which correspond to the side chains of the arabinogalactan, beta-Galp-(1-->4)-beta-Galp-(1-->4)-beta-Galp-(1-->4)-Gal; and a mixture of beta-Galp-(1-->4)-beta-Galp-(1-->4)-Gal and beta-Glcp-(1-->4)-beta-Galp-(1-->4)-beta-Galp-(1-->4)-Gal, which did not resemble side-chain structures of the arabinogalactan. The latter are suggested to be related to tragacanthic acid, which has been previously found to contain beta-Galp nonreducing end-units.

Fungal cell wall galactomannan isolated from Apodus deciduus

The alkali-extractable water-soluble polysaccharide (F1SS) isolated from the cell wall of Apodus deciduus has been studied by methylation analysis and NMR spectroscopy, and its structure established as:where n approximately 130+/-10.

Structural study on lipid A and the O-specific polysaccharide of the lipopolysaccharide from a clinical isolate of Bacteroides vulgatus from a patient with Crohn's disease

Bacteroides vulgatus has been shown to be involved in the aggravation of colitis. Previously, we separated two potent virulence factors, capsular polysaccharide (CPS) and lipopolysaccharide (LPS), from a clinical isolate of B. vulgatus and characterized the structure of CPS. In this study, we elucidated the structures of O-antigen polysaccharide (OPS) and lipid A in the LPS. LPS was subjected to weak acid hydrolysis to produce the lipid A fraction and polysaccharide fraction. Lipid A was isolated by preparative TLC, and its structure determined by MS and NMR to be similar to that of Bacteroides fragilis except for the number of fatty acids. The polysaccharide fraction was subjected to gel-filtration chromatography to give an OPS-rich fraction. The structure of OPS was determined by chemical analysis and NMR spectroscopy to be a polysaccharide composed of the following repeating unit: [-->4)alpha-L-Rhap(1-->3)beta-D-Manp(1-->].

Chemical transformation of lactose into 4-O-beta-D-galactopyranosyl-D-glucuronic acid (pseudolactobiouronic acid) and some derivatives thereof

The selective oxidation of the primary alcoholic function of the reducing unit of lactose was achieved in good overall yield (67%) starting from 2',6'-di-O-benzyl-2,3:3',4'-di-O-isopropylidenelactose dimethyl acetal (1) through a simple multi-step procedure based on the selective acetylation of OH-5 of 1 (methoxyisopropylation, acetylation, de-methoxyisopropylation) followed by a two-step oxidation at C-6 (TPAP-NMO then TEMPO-NaOCl) and finally, complete removal of the protecting groups.

Molecular dynamics of polycrystalline cellobiose studied by solid-state NMR

Molecular motions of polycrystalline cellobiose have been investigated by measuring proton spin-lattice relaxation times, T1 and T1rho, and the second moment, M2, in both protonated and D2O exchanged forms over the temperature range 120-380 K. T1 relaxation is dominated by the motions of hydroxyl groups between 150 and 380 K, characterised by an activation energy of about 8.74 kJ/mol, whereas T1rho relaxation is driven by the motions of the same groups between 120 and 300 K. T1rho results suggest that hydroxyl groups have a distribution of dynamics. Motion of methylene groups was detected in the second-moment experiments at about 350 K, characterised by activation energy of about 40 kJ/mol. Consideration of the calculated and observed rigid-lattice second moments suggests that the reported X-ray data are incorrect for the inter-proton distance on C6'. 13C CPMAS spectra of both protonated and deuterated cellobiose have also been measured. Spectra of the deuterated material showed the existence of a second crystalline form in addition to the normal form.

Sulfated polysaccharides from the red seaweed Georgiella confluens

The water-soluble polysaccharides from Georgiella confluens, collected in Antarctica, were fractionated with cetrimide. The complexed material was subjected to fractional solubilization in solutions of increasing sodium chloride concentration. The initially extracted polysaccharide and the major fraction isolated, soluble in 0.5 M NaCl, were studied. These are sulfated xylogalactans naturally rich in methylated sugar residues, comprising of 3,6-anhydro-2-O-methyl-L-galactose, 2-O-methyl-L-galactose and 6-O-methyl-D-galactose. Structural analysis was carried out by methylation, ethylation, desulfation-ethylation, desulfation-methylation, Smith degradation, 13C NMR spectroscopy and determination of the absolute configuration of monosaccharides by gas chromatography of diastereomeric derivatives produced by reductive amination. The results indicated the presence of an agaran backbone with an unusual substitution pattern: sulfation mainly at the 3-position of the alpha-L-galactose units and the presence of xylose side chains at the 4-position of the beta-D-galactose residues.

Structural characterization of the O-antigenic polysaccharide chain of Porphyromonas circumdentaria NCTC 12469

Structural studies were carried out on an O-antigenic polysaccharide moiety derived from Porphyromonas circumdentaria NCTC 12469, a reference strain of Porphyromonas species. The polysaccharide chain was composed of D-glucose, D-galactose, N-acetyl-D-glucosamine, and N-acetyl-D-galactosamine in a molar ratio of 1:2:1:1. On the basis of results from 1H- and 13C-NMR spectroscopic analyses including COSY, TOCSY, and HMQC experiments together with results of Smith degradation, methylation analysis, and partial acid hydrolysis, it is concluded that the polysaccharide chain has a pentasaccharide repeating unit of -->6)-beta-D-Glcp-(1-->6)-beta-D-Galp-(1-->3)-beta-D-GlcpNAc-(1-->3)-beta-D-GalpNAc-(1-->. The immunoreaction between P. circumdentaria LPS and the corresponding antiserum was strongly inhibited by the pentasaccharide fragment (Glc-Gal-Gal-GlcNAc-GalNAc) isolated from partial acid hydrolysis of the above polysaccharide, suggestive of O-antigen specific antibodies in the used antiserum.

N-Methylation in polylegionaminic acid is associated with the phase-variable epitope of Legionella pneumophila serogroup 1 lipopolysaccharide. Identification of 5-(N,N-dimethylacetimidoyl)amino and 5-acetimidoyl(N-methyl)amino-7-acetamido-3,5,7,9-tetradeoxynon-2-ulosonic acid in the O-chain polysaccharide

Previously, a phase-variable epitope was detected in the virulent wild-type strain RC1 of Legionella pneumophila serogroup 1 subgroup OLDA using a lipopolysaccharide-specific monoclonal antibody, mAb 2625 [Lüneberg, E., Zähringer, U., Knirel, Y. A., Steinmann, D., Hartmann, M., Steinmetz, I., Rohde, M., Kohl, J. & Frosch, M. (1998) J.Exp. Med. 188, 49-60]. In the present study, an isogenic mutant strain, termed 5215, was constructed by deletion of genes involved in the biosynthesis of the mAb 2625 epitope. Mutant 5215 was as virulent as the parental wild-type RC1 but did not bind mAb 2625. The two strains showed no difference in the core oligosaccharide and lipid A but in the O-chain polysaccharide structure, which is a homopolymer of 5-acetimidoylamino-7-acetamido-3,5,7,9-tetradeoxy-d-glycero-d-galacto-non-2-ulosonic acid (a derivative of legionaminic acid). NMR spectroscopic studies revealed a hitherto unknown modification of bacterial polysaccharides in the wild-type strain, namely N-methylation of the 5-acetimidoylamino group on a single legionaminic acid residue that is located, most likely, proximal to the core oligosaccharide. Two major N-methylated substituents, the (N,N-dimethylacetimidoyl)amino and acetimidoyl(N-methyl) amino groups, could be allocated to the long- and middle-chain O-polysaccharide species, respectively. N-Methylation of legionaminic acid that was absent from the isogenic mutant 5215 and from the spontaneous phase variant 811, correlated with the presence of the mAb 2625 epitope.

Isolation, enzymatic properties, and mode of action of an exo-1,3-beta-glucanase from Trichoderma viride

An exo-1,3-beta-glucanase has been isolated from cultural filtrate of T. viride AZ36. The N-terminal sequence of the purified enzyme (m = 61 +/- 1 kDa) showed no significant homology to other known glucanases. The 1,3-beta-glucanase displayed high activity against laminarins, curdlan, and 1,3-beta-oligoglucosides, but acted slowly on 1,3-1,4-beta-oligoglucosides. No significant activity was detected against high molecular mass 1,3-1,4-beta-glucans. The enzyme carried out hydrolysis with inversion of the anomeric configuration. Whereas only glucose was released from the nonreducing terminus during hydrolysis of 1,3-beta-oligoglucosides, transient accumulation of gentiobiose was observed during hydrolysis of laminarins. The gentiobiose was subsequently degraded to glucose. The Michaelis constants Km and Vmax have been determined for the hydrolysis of 1,3-beta-oligoglucosides with degrees of polymerization ranging from 2 to 6. Based on these data, binding affinities for subsites were calculated. Substrate binding site contained at least five binding sites for sugar residues.

An antifungal exo-alpha-1,3-glucanase (AGN13.1) from the biocontrol fungus Trichoderma harzianum

Trichoderma harzianum secretes alpha-1,3-glucanases when it is grown on polysaccharides, fungal cell walls, or autoclaved mycelium as a carbon source (simulated antagonistic conditions). We have purified and characterized one of these enzymes, named AGN13.1. The enzyme was monomeric and slightly basic. AGN13.1 was an exo-type alpha-1,3-glucanase and showed lytic and antifungal activity against fungal plant pathogens. Northern and Western analyses indicated that AGN13.1 is induced by conditions that simulated antagonism. We propose that AGN13.1 contributes to the antagonistic response of T. harzianum.

Heterologous expression and characterization of the exopolysaccharide from Streptococcus thermophilus Sfi39

The genes responsible for exopolysaccharide (EPS) synthesis in Streptococcus thermophilus Sfi39 were identified on a 20-kb genomic fragment. The two genes, epsE and epsG, were shown to be involved in EPS synthesis as their disruption lead to the loss of the ropy phenotype. Several naturally selected nonropy mutants were isolated, one acquired an insertion sequence (IS)-element (IS905) in the middle of the eps gene cluster. The eps gene cluster was cloned and transferred into a nonEPS-producing heterologous host, Lactococcus lactis MG1363. The EPS produced was shown by chemical analysis and NMR spectroscopy to be identical to the EPS produced by S. thermophilus Sfi39. This demonstrated first that all genes needed for EPS production and export were present in the S. thermophilus Sfi39 eps gene cluster, and second that the heterologous production of an EPS was possible by transfer of the complete eps gene cluster alone, provided that the heterologous host possessed all necessary genetic information for precursor synthesis.

Biosynthesis of (1-->3)-beta-D-glucan (callose) by detergent extracts of a microsomal fraction from Arabidopsis thaliana

The aim of this work was to develop a biochemical approach to study (1-->3)-beta-D-glucan (callose) biosynthesis using suspension cultures of Arabidopsis thaliana. Optimal conditions for in vitro synthesis of callose corresponded to an assay mixture containing 50 mM Mops buffer, pH 6.8, 1 mM UDP-glucose, 8 mM Ca2+ and 20 mM cellobiose. The enzyme was Ca2+-dependent, and addition of Mg2+ to the reaction mixture did not favour cellulose biosynthesis. Enzyme kinetics suggested the existence of positive homotropic cooperativity of (1-->3)-beta-D-glucan synthase for the substrate UDP-glucose, in agreement with the hypothesis that callose synthase consists of a multimeric complex containing several catalytic subunits. Detergents belonging to different families were tested for their ability to extract and preserve membrane-bound (1-->3)-beta-D-glucan synthase activity. Cryo-transmission electron microscopy experiments showed that n-octyl-beta-D-glucopyranoside allowed the production of micelle-like structures, whereas vesicles were obtained with Chaps and Zwittergent 3-12. The morphology and size of the (1-->3)-beta-D-glucans synthesized in vitro by fractions obtained with different detergents were affected by the nature of the detergent tested. These data suggest that the general organization of the glucan synthase complexes and the properties of the in vitro products are influenced by the detergent used for protein extraction. The reaction products synthesized by different detergent extracts were characterized by infrared spectroscopy, methylation analysis, 13C-NMR spectroscopy, electron microscopy and X-ray diffraction. These products were identified as linear (1-->3)-beta-D-glucans having a degree of polymerization higher than 100, a microfibrillar structure, and a low degree of crystallinity.

Structural analysis of the polysaccharide from the lipopolysaccharide of Porphyromonas gingivalis strain W50

The lipopolysaccharide (LPS) of Porphyromonas gingivalis is an important pro-inflammatory molecule in periodontal disease and a significant target of the host's specific immune response. In addition, we recently demonstrated using monoclonal antibodies that the Arg-gingipains of P. gingivalis are post-translationally modified with glycan chains that are immunologically related to an LPS preparation from this organism. In the present investigation, we determined the structure of the O-polysaccharide of P. gingivalis W50 that was fully characterized on the basis of 1D and 2D NMR (DQF-COSY, TOCSY, NOESY, ROESY, 1H-13C HSQC and 1H-31P HXTOCSY) and GC-MS data. These data allowed us to conclude that the O-polysaccharide is built up of the tetrasaccharide repeating sequence: -->6)-alpha-D-Glcp-(1-->4)-alpha-L-Rhap-(1-->3)-beta-D-GalNAc-(1-->3)-alpha-D-Galp-(1--> and carries a monophosphoethanolamine residue at position C-2 of the alpha-rhamnose residue in a nonstoichiometric (approximately 60%) amount. These data indicate that the O-polysaccharide of P. gingivalis LPS is composed of an unusually modified tetrasaccharide repeating unit.

Structure of a cell wall polysaccharide isolated from Hypocrea gelatinosa

The structure of a polysaccharide isolated from the cell wall of Hypocrea gelatinosa has been investigated by means of chemical analyses and 1D and 2D NMR spectroscopy. The polysacharide has an irregular structure, idealized as follows: [carbohydrate structure in text].

Comparison of cell-wall polysaccharides from Nectria cinnabarina with those from the group of Nectria with Sesquicillium anamorphs

Alkali-extractable and water-soluble polysaccharides were purified from cell walls of five species of Sesquicillium or its teleomorphs, Nectria lasiacidis and Nectria impariphialis, and from Nectria cinnabarina, the type species of Nectria, a heterogeneous genus that belongs to the Hypocreales. Methylation and NMR analyses for determination of linkage types and structure were performed and indicated differences between the polysaccharides purified during the present study and those isolated from other nectrioid fungi, namely the presence of 5-O-substituted galactofuranose (-->5)-Galf-(1-->) in the main chain together with 2,6-di-O-substituted galactofuranose (-->2,6)-Galf-(1-->) residues in Sesquicillium buxi and Sesquicillium pseudosetosum. The polysaccharide from N. impariphialis was similar to those obtained from the above species, although an additional residue of 6-O-substituted glucopyranose (-->6)-Glcp-(1-->), was detected in some side chains. In N. lasiacidis and Sesquicillium candelabrum the polysaccharide contained an additional branching point of 5,6-di-O-substituted galactofuranose (-->5,6)-Galf-(1-->) linked to terminal N-acetylglucosamine GlcNAc-(1-->). These chains were linked to a small mannan core. All these polysaccharides showed major differences to the polysaccharide of N. cinnabarina, which was formed by a main chain of (1-->6)-beta-linked galactofuranose units almost fully branched at positions 2-O by either single residues of glucopyranose or acidic chains containing glucuronic acid and mannose.

Concurrent maltodextrin and cellodextrin synthesis by Fibrobacter succinogenes S85 as identified by 2D NMR spectroscopy

1D and 2D NMR experiments were used to analyse the synthesis of various metabolites by resting cells of Fibrobacter succinogenes S85 when incubated with [1-(13)C]glucose, in both extracellular and cellular media. Besides the expected glycogen, succinate, acetate, glucose-1-P and glucose-6-P, maltodextrins and cellodextrins were detected. Maltodextrins were excreted into the external medium. They were found to have linear structures with a maximum degree of polymerization (DP) of about 6 or 7 units. Cellodextrins were located in the cells (cytoplasm and/or periplasm), and their DP was < or = 4. Both labelled (1-(13)C and 6-(13)C) and unlabelled maltodextrins and cellodextrins were detected, showing the contribution of carbohydrate cycling in F. succinogenes, including the reversal of glycolysis and the futile cycle of glycogen. The mechanisms of these oligosaccharide syntheses are discussed.

Purification and characterisation of a galactoglucomannan from kiwifruit (Actinidia deliciosa)

A galactoglucomannan (GGM) has been purified from the primary cell walls of ripe kiwifruit. A combination of barium hydroxide precipitation, anion exchange- and gel-permeation chromatography gave a chemically homogeneous polymer with a 1:2:2 galactose-glucose-mannose ratio and a molecular weight range of 16-42 kDa. Complete hydrolysis of the polymer with endo-1,4-beta-mannanase (EC 3.2.1.78) from Aspergillus niger gave a mixture of oligosaccharides, three of which (II, III, IV) accounted for more than 80% of the GGM. Structural characterisation of these oligosaccharides and the original polysaccharide was achieved by linkage analysis, 1D and 2D NMR spectrometry and enzymatic hydrolysis. Oligosaccharide II beta-D-Glcp-(1-->4)-beta-D-Manp-(1-->, III beta-D-Glcp-(1-->4)-[alpha-D-Galp-(1-->6)]-beta-D-Manp-(1-->, and IV beta-D-Glcp-(1-->4)-[beta-D-Galp-(1-->2)-alpha-D-Galp-(1-->6)]-beta-D-Manp-(1-->4)-beta-D-Glcp-(1-->4)-beta-D-Manp-(1-->, appeared in the molar ratio of 2:1:1. A trace amount of mannobiose (I) was detected, indicating that some of the mannosyl residues were contiguous. It is concluded that the predominant structural feature of kiwifruit GGM is a backbone of alternating beta-(1-->4)-linked D-glucopyranosyl and D-mannopyranosyl residues, with approximately one third of the latter carrying side-chains at 0-6 of single alpha-D-Galp-(1--> residues (50% of the branches) or the disaccharide beta-D-Galp-(1-->2)-alpha-D-Galp-(1--> (50% of the branches), the substituted residues being separated by three or five unsubstituted monosaccharide units.

DL-Galactan hybrids and agarans from gametophytes of the red seaweed gymnogongrus torulosus

Seaweeds from the genus Gymnogongrus are known to be carrageenophytes; nevertheless, fractionation techniques used previously for the separation of gel-forming and 'soluble' carrageenans, applied to the galactans of Gymnogongrus torulosus together with enantiomeric analysis of the sugar components and (when possible) of the structural units, suggested that the system of galactans biosynthesized by the seaweed was formed by DL-galactan hybrids having major amounts of carrageenan-type or agaran-type chains, with minor quantities of agarans with unusual structural details.

Structural characterization of the glycan part of glycoconjugate LbGp2 from Lycium barbarum L

A glycoconjugate with pronounced immunoactivity, designated as LbGp2, was isolated from the fruit of Lycium barbarum L. and purified to homogeneity by gel-filtration. Its carbohydrate content is up to 90.71% composed of Ara, Gal and amino acids. The molecular weight is 68.2 kDa as determined by size exclusive chromatography (SEC). The complete structure of the repeat unit of the glycan of LbGp2 was elucidated based on glycosidic linkage analysis, total acid hydrolysis, partial acid hydrolysis, 1H and 13C NMR spectroscopy. According to the experiments, the glycan possesses a backbone consisting of (1-->6)-beta-galactosyl residues, about fifty percent of which are substituted at C-3 by galactosyl or arabinosyl groups and the major nonreducing end being made of Ara (1 -->.

Human alpha3-fucosyltransferases convert chitin oligosaccharides to products containing a GlcNAcbeta1-4(Fucalpha1-3)GlcNAcbeta1-4R determinant at the nonreducing terminus

Human alpha3-fucosyltransferases (Fuc-Ts) are known to convert N-acetyllactosamine to Galbeta1-4(Fucalpha1-3)GlcNAc (Lewis x antigen); some of them transfer fucose also to GalNAcbeta1-4GlcNAc, generating GalNAcbeta1-4(Fucalpha1-3)GlcNAc determinants. Here, we report that recombinant forms of Fuc-TV and Fuc-TVI as well as Fuc-Ts of human milk converted chitin oligosaccharides of 2-4 GlcNAc units efficiently to products containing a GlcNAcbeta1-4(Fucalpha1-3)GlcNAcbeta1-4R determinant at the nonreducing terminus. The product structures were identified by mass spectrometry and nuclear magnetic resonance experiments; rotating frame nuclear Overhauser spectroscopy data suggested that the fucose and the distal N-acetylglucosamine are stacked in the same way as the fucose and the distal galactose of the Lewis x determinant. The products closely resembled a nodulation factor of Mesorhizobium loti but were distinct from nodulation signals generated by NodZ-enzyme.

Investigation of bacterial spore structure by high resolution solid-state nuclear magnetic resonance spectroscopy and transmission electron microscopy

High resolution solid-state nuclear magnetic resonance spectroscopy (NMR) in combination with transmission electron microscopy (TEM) of spores of Bacillus cereus, an outer coatless mutant B. subtilis 322, an inner coatless mutant B. subtilis 325 and of germinated spores of B. subtilis CMCC 604 were carried out. Structural differences in the coats, mainly protein of spores were reflected by NMR spectra which indicated also differences in molecular mobility of carbohydrates which was partially attributed to the cortex. Dipicolinic acid (DPA) of spores of B. cereus displayed a high degree of solid state order and may be crystalline. Heat activation was studied on spores of B. subtilis 357 lux + and revealed a structural change when analysed by TEM but this was not associated with increases in molecular mobility since no effects were measured by NMR.

Galactoglucomannan from the secondary cell wall of Picea abies L. Karst

The fine structural features of alkali-extracted galactoglucomannan composed of D-galactose, D-glucose and D-mannose in a 1:8:33 mole proportion from the secondary cell walls of Picea abies L. Karst have been determined. Compositional and methylation analyses of the polymer, partial acid hydrolysis, as well as 1H and 13C NMR measurements of the polymer and products of partial acid hydrolysis confirmed a beta-(1-->4)-linked backbone of galactoglucomannan containing the segments of mannosyl residues (Man2, Man3, Man4, etc.) interrupted with the segments having both mannose and glucose residues, as well as the segments in which D-Glcp units can be adjacent to each other (Glc2). Further, the low content of branching points (approximately 3%) at the positions of 0-6, 0-3 and 0-2 of mannosyl and 0-6 and 0-3 of glucosyl residues, but preferably of mannosyl ones, indicates the presence of short side-chains terminated at position 0-6 predominantly by D-galactose units as single stubs.

Molecular structure of fagopyritol A1 (O-alpha-D-galactopyranosyl-(1 --> 3)-D-chiro-inositol) by NMR

The molecular structure of fagopyritol A1, a novel galactopyranosyl cyclitol from buckwheat seeds, was determined to be O-alpha-D-galactopyranosyl-(1 --> 3)-D-chiro-inositol by 1H and 13C NMR. Fagopyritol A1 is a positional isomer of fagopyritol B1 (O-alpha-D-galactopyranosyl-(1 --> 2)-D-chiro-inositol), representing a different series of fagopyritol oligomers. Trimethylsilyl derivatives of both compounds have similar mass spectra, but each may be identified by different abundance ratios of fragments with m/z 305/318 and 318/319.

Cytochrome b558/566 from the archaeon Sulfolobus acidocaldarius has a unique Asn-linked highly branched hexasaccharide chain containing 6-sulfoquinovose

Cytochrome b558/566 from the archaeon Sulfolobus acidocaldarius (DSM 639) has been described as a novel highly glycosylated membrane-bound b-type hemoprotein [Hettmann, T., Schmidt, C. L., Anemüller, S., Zähringer, U., Moll, H., Petersen, A. & Schäfer, G. (1998) J. Biol. Chem. 273, 12032-12040]. The purified cytochrome b558/566 was characterized by MALDI MS as a 64-kDa (glyco)protein expressing 17% glycosylation. Detailed chemical studies showed that it was exclusively O-mannosylated with monosaccharides and N-glycosylated with at least seven hexasaccharide units having the same unique structure. The hexasaccharide was released by cleavage with peptide:N-glycosidase (PNGase) F and found to consist of two residues each of Man and GlcNAc and one residue each of Glc and 6-deoxy-6-sulfoglucose (6-sulfoquinovose). The last sugar has been known as a component of glycolipids of plants and some prokaryotes, but has not been hitherto found in bacterial glycoproteins. Digestion with trypsin/pronase gave a mixture of glycopeptides with the same Asn-linked hexasaccharide chain, from which an N-glycosylated Tyr-Asn dipeptide was purified by gel chromatography and anion-exchange HPLC. Studies of the degradation products using methylation analysis, ESI MS, MALDI MS, and 1H and 13C NMR spectroscopy, including 1H,13C HMQC and NOESY experiments, established the structure of the unique Asn-linked hexasaccharide chain of cytochrome b558/566.

The system of low-molecular-weight carrageenans and agaroids from the room-temperature-extracted fraction of Kappaphycus alvarezii

The room-temperature-extracted fraction from the red seaweed Kappaphycus alvarezii consists mainly of low-molecular-weight carrageenans, with structural dispersion around a basic kappa-pattern. This dispersion results from: (a) low percentages of 3,6-anhydrogalactose and the presence of precursor units; (b) important quantities of 6-O-methyl beta-D-galactose (4-sulfate) residues; (c) significant amounts of iota-repeating structure, and (d) small amounts of non-sulfated and disulfated beta-D-galactose residues. Significant quantities of alpha-L-galactose units suggest the presence of agaroids, as it has been reported in several other carrageenophytes.

Identification and synthesis of a trisaccharide produced from lactose by transgalactosylation

Enzymatic transgalactosylation of lactose by means of Streptococcus thermophilus, subspecies DN-001065, led to a mixture of D-galactose (approximately 4%), D-glucose (approximately 15%), lactose (approximately 51%), minor disaccharides (6%), trisaccharides (approximately 20%) and tetrasaccharides (3%). The major trisaccharide (approximately 16%) was identified by NMR spectroscopy and chemical synthesis as being the known beta-D-galactopyranosyl-(1-->3)-beta-D-galactopyranosyl-(1-->4)-D-glucos e (3'-beta-D-galactopyranosyl-lactose). It was purified from a mixture of peracetylated oligosaccharides by column chromatography followed by deacetylation. For the first time, 3'-beta-D-galactopyranosyl-lactose has been obtained on the 1 g scale, by resorting to simple techniques and equipment. NMR spectra have been unambiguously assigned.

Amylosucrase from Neisseria polysaccharea: novel catalytic properties

Amylosucrase is a glucosyltransferase that synthesises an insoluble alpha-glucan from sucrose. The catalytic properties of the highly purified amylosucrase from Neisseria polysaccharea were characterised. Contrary to previously published results, it was demonstrated that in the presence of sucrose alone, several reactions are catalysed, in addition to polymer synthesis: sucrose hydrolysis, maltose and maltotriose synthesis by successive transfers of the glucosyl moiety of sucrose onto the released glucose, and finally turanose and trehalulose synthesis - these two sucrose isomers being obtained by glucosyl transfer onto fructose. The effect of initial sucrose concentration on initial activity demonstrated a non-Michaelian profile never previously described.

Extracellular polysaccharide of Erwinia chrysanthemi A350 and ribotyping of Erwinia chrysanthemi spp

Erwinia chrysanthemi spp. are gram-negative bacterial phytopathogens causing soft rots in a number of plants. The structure of the extracellular polysaccharide (EPS) produced by the E. chrysanthemi strain A350, which is a lacZ- mutant of the wild type strain 3937, pathogenic to Saintpaulia, has been determined using a combination of chemical and physical techniques including methylation analysis, low-pressure gel-filtration and anion-exchange chromatography, high-pH anion-exchange chromatography, partial acid hydrolysis, mass spectrometry and 1- and 2D NMR spectroscopy. In contrast to the structures of the EPS reported for other strains of E. chrysanthemi, the EPS from strain A350 contains D-GalA, together with L-Rhap and D-Galp in a 1:4:1 ratio. Evidence is presented for the following hexasaccharide repeat unit: [structure: see text] All the Erwinia chrysanthemi spp. studied to date have been analyzed by ribotyping and collated into families, which are consistent with the related structures of their EPS.

Effects of various saccharides on cycloinulo-oligosaccharide fructanotransferase reaction: production of beta-inulotriosyl-alpha-D-mannopyranoside and 1-O-beta-inulotriosyl-alpha-L-sorbopyranose

The effects of various saccharides on the reaction of cycloinulo-oligosaccharide fructanotransferase with cycloinu-lohexaose were examined. In addition to beta-D-fructofuranosides and methyl alpha-D-glucopyranoside, D-mannose and L-sorbose were found to be effective acceptors in the reactions, and they enhanced the hydrolytic activity as effectively as methyl alpha-D-glucopyranoside. Hetero-tetrasaccharides were isolated as the major transfer products from both reaction mixtures. The isolates were identified by NMR spectroscopy as beta-inulotriosyl-alpha-D-mannopyranoside and 1-O-beta-inulotriosyl-alpha-L-sorbopyranose. Methyl beta-D-glucopyranoside was slightly effective and methyl alpha-D-mannopyranoside was not effective at all as the acceptor, but these saccharides strongly enhanced the hydrolytic activity. D-Glucosamine inhibited the enzyme activity.

A transglycosylating 1,3(4)-beta-glucanase from rhodothermus marinus NMR analysis of enzyme reactions

The enzymatic hydrolysis of polysaccharides by the 1, 3(4)-beta-glucanase (LamR) from Rhodothermus marinus has been explored. The enzyme cleaves the 1,3-beta-linkages of 3-O-substituted glucose units in 1,3-beta-glucans such as laminarin and curdlan, and also the 1,4-beta-linkages of 3-O-substituted beta-glucose in beta-glucans such as lichenin and 1,3-1, 4-beta-glucan from the cell walls of barley endosperm. The polysaccharide substrates (laminarin, curdlan and barley beta-glucan) were characterised using NMR spectroscopy. The reaction of LamR with its substrates was followed by recording one-dimensional and two-dimensional 1H-NMR and 13C-NMR spectra at suitable time intervals after addition of the enzyme. It is shown that hydrolysis occurs with retention of the anomeric configuration and that LamR performs transglycosylation to generate both 1, 3-beta-glycosidic and 1,4-beta glycosidic linkages. The transglycosylation results in, e.g. formation of the trisaccharide 4-O-glucosyl-laminaribiose from exclusively 1,3-beta-oligoglucosides. When barley 1,3-1,4-beta-glucan was incubated with LamR the beta-1, 4-linkages of 3-O-substituted beta-glycosyl residues were rapidly hydrolysed. Simultaneously de novo formation of 1,3-beta-glycosidic linkages was observed which, however, were cleaved during prolonged incubations. It is shown that a laminaribiosyl unit is the minimum requirement for formation of an enzyme-substrate complex and subsequent hydrolysis/transglycosylation.

The structure of the colony migration factor from pathogenic Proteus mirabilis. A capsular polysaccharide that facilitates swarming

Swarming by Proteus mirabilis is characterized by cycles of rapid and coordinated population migration across surfaces following differentiation of vegetative cells into elongated hyperflagellated swarm cells. It has been shown that surface colony expansion by the swarm cell population is facilitated by a colony migration factor (Cmf), a capsular polysaccharide (CPS) that also contributes to the uropathogenicity of P. mirabilis (Gygi, D., Rahman, M. M., Lai, H.-C., Carlson, R., Guard-Petter, J., and Hughes, C. (1995) Mol. Microbiol. 17, 1167-1175). In this report, the Cmf-CPS was extracted with hot water, precipitated with ethanol, and further purified by gel permeation chromatography. Its structure was established by glycosyl composition and linkage analyses, and by one- and two-dimensional NMR spectroscopy. The Cmf-CPS is composed of the following tetrasaccharide repeating unit. [see text]

Chemical synthesis of 6"'-alpha-maltotriosyl-maltohexaose as substrate for enzymes in starch biosynthesis and degradation

A branched nonasaccharide 6"'-alpha-maltotriosyl-maltohexaose was synthesised in 40 steps from D-glucose and maltose. Phenyl O-(2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranosyl)-(1-->4)-O- (2,3,6-tri-O-benzyl-alpha-D-glucopyranosyl)-(1-->4)-2,3-di-O-benzyl-1-th io- beta-D-glucopyranoside and O-(2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranosyl)-(1-->4)-O-(2,3,6-tri- O-benzyl-alpha-D-glucopyranosyl)-(1-->4)-2,3,6-tri-O-benzyl-alpha, beta-D-glucopyranosyl trichloroacetimidate were coupled by a general condensation reaction to form the per-O-benzylated branched hexasaccharide phenyl thioglycoside. The phenylthio group of this compound was converted into a trichloroacetimidate, which was coupled with phenyl O-(2,3,6-tri-O-benzyl-alpha-D-glucopyranosyl)-(1-->4)-O-(2,3,6-tri-O- benzyl-alpha-D-glucopyranosyl)-(1-->4)-2,3,6-tri-O-benzyl-1-thio-beta-D- glucopyranoside to afford the per-O-benzylated branched nonasaccharide phenyl thioglycoside. Replacement of the phenylthio group with a free OH-group followed by hydrogenolysis gave the desired product. The synthons reported for this synthesis constitute a versatile tool for the chemical synthesis of other complex carbohydrates.

Introduction of the exopolysaccharide gene cluster from Streptococcus thermophilus Sfi6 into Lactococcus lactis MG1363: production and characterization of an altered polysaccharide

Streptococcus thermophilus Sfi6 produces an exopolysaccharide (EPS) composed of glucose, galactose and N-acetylgalactosamine in the molar ratio of 1:2:1. The genes responsible for the EPS biosynthesis have been isolated previously and found to be clustered in a 14.5 kb region encoding 13 genes. Transfer of this gene cluster into a non-EPS-producing heterologous host, Lactococcus lactis MG1363, yielded an EPS with a similar high molecular weight, but a different structure from the EPS from the native host. The structure of the recombinant EPS was determined by means of 1H homonuclear and 1H-13C heteronuclear two-dimensional nuclear magnetic resonance (NMR) spectra and was found to be --> 3)-beta-D-Glcp-(1 --> 3)-alpha-D-Galp-(1 --> 3)-beta-D-Galp-(1 --> as opposed to --> 3)[alpha-D-Galp-(1 --> 6)]-beta-D-Glcp-(1 --> 3)-alpha-D-GalpNAc-(1 --> 3)-beta-D-Galp-(1 --> for the wild-type S. thermophilus Sfi6. Furthermore, L. lactis MG1363 (pFS101) was also lacking a UDP-N-acetylglucosamine C4-epimerase activity, which would provide UDP-GalNAc for a GalNAc incorporation into the EPS and probably caused the substitution of GalNAc by Gal in the recombinant EPS. This modification implies that (i) bacterial glycosyltransferases could potentially have multiple specificities for the donor and the acceptor sugar molecule; and (ii) the repeating unit polymerase can recognize and polymerize a repeating unit that differs in the backbone as well as in the side-chain from its native substrate.