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Bent O Petersen

Publications and source records attributed to Bent O Petersen.

15 recordsLinked to original sources
PubMed2006

Structural characterisation of novel lichen heteroglycans by NMR spectroscopy and methylation analysis.

Two galactofuranomannans, Ths-4 and Ths-5, were isolated from the lichen, Thamnolia vermicularis var. subuliformis, using ethanol fractionation and anion-exchange and size-exclusion chromatography. The average molecular weights of Ths-4 and Ths-5 were estimated to be 19 and 200 kDa, respectively. Structural characterisation of Ths-4, Ths-5 and their partially hydrolysed derivatives was performed by methanolysis and methylation analysis. The intact and partially hydrolysed Ths-4 was further analysed using NMR spectroscopy (1D, COSY, NOESY, TOCSY, HSQC and HMBC). According to the data obtained, the heteroglycans Ths-4 and Ths-5 have similar structures, but have large differences in molecular weight. The structure is composed of 3-O-linked and 5-O-linked galactofuranosyl chains linked to a mannan core. The mannan core consists of a main chain of alpha-(1-->6)-linked mannopyranosyl residues, substituted at O-2 with either a single alpha-mannopyranosyl unit or an alpha-Manp-(1-->2)-alpha-Manp-(1-->2)-alpha-Manp group in the ratio of approximately 1:3, respectively. The polysaccharides have idealised repeating blocks as is shown.

Chromatography, Ion Exchange↗
PubMed2006

Characterization of the lipopolysaccharide and beta-glucan of the fish pathogen Francisella victoria.

Lipopolysaccharide (LPS) and beta-glucan from Francisella victoria, a fish pathogen and close relative of highly virulent mammal pathogen Francisella tularensis, have been analyzed using chemical and spectroscopy methods. The polysaccharide part of the LPS was found to contain a nonrepetitive sequence of 20 monosaccharides as well as alanine, 3-aminobutyric acid, and a novel branched amino acid, thus confirming F. victoria as a unique species. The structure identified composes the largest oligosaccharide elucidated by NMR so far, and was possible to solve using high field NMR with cold probe technology combined with the latest pulse sequences, including the first application of H2BC sequence to oligosaccharides. The non-phosphorylated lipid A region of the LPS was identical to that of other Francisellae, although one of the lipid A components has not been found in Francisella novicida. The heptoseless core-lipid A region of the LPS contained a linear pentasaccharide fragment identical to the corresponding part of F. tularensis and F. novicida LPSs, differing in side-chain substituents. The linkage region of the O-chain also closely resembled that of other Francisella. LPS preparation contained two characteristic glucans, previously observed as components of LPS preparations from other strains of Francisella: amylose and the unusual beta-(1-6)-glucan with (glycerol)2phosphate at the reducing end.

Alanine↗
PubMed2006

Complete structures of Bordetella bronchiseptica and Bordetella parapertussis lipopolysaccharides.

The structures of the lipopolysaccharide (LPS) core and O antigen of Bordetella bronchiseptica and Bordetella parapertussis are known, but how these two regions are linked to each other had not been determined. We have studied LPS from several strains of these microorganisms to determine the complete carbohydrate structure of the LPS. LPS was analyzed using different chemical degradations, NMR spectroscopy, and mass spectrometry. This identified a novel pentasaccharide fragment that links the O chain to the core in all the LPS studied. In addition, although the O chain of these bacteria was reported as a homopolymer of 1,4-linked 2,3-diacetamido-2,3-dideoxy-alpha-galacturonic acid, we discovered that the polymer contains several amidated uronic acids, the number of which varies between strains. These new data describe the complete structure of the LPS carbohydrate backbone for both Bordetella species and help to explain the complex genetics of LPS biosynthesis in these bacteria.

Bordetella bronchiseptica↗
PubMed2006

H2BC: a new technique for NMR analysis of complex carbohydrates.

It is demonstrated that the H2BC NMR pulse sequence (J. Am. Chem. Soc.2005, 127, 6154, Magn. Reson. Chem.2005, 43, 971-974) offers unambiguous assignments and significant simplification of NMR spectra of large and complex carbohydrates compared to other techniques for the establishment of correlations over more than one bond. H2BC almost exclusively correlates protons and proton-bearing carbon spins separated by two covalent bonds and is independent of occasionally vanishing (2)J(CH) coupling constants, which alleviates the problem of missing two-bond correlations in HMBC spectra. H2BC also solves the problem of distinguishing two- and three-bond correlations in HSQC-TOCSY or HMBC. It is a further asset of H2BC that the experiment is significantly shorter than HMBC and HSQC-TOCSY, and hence less sensitive to transverse relaxation. The H2BC experiment is demonstrated on an approximately 30-residue oligosaccharide from Francisella victoria.

Carbohydrates↗
PubMed2005

Substrate specificity of the bovine serum amine oxidase and in situ characterisation of aminoaldehydes by NMR spectroscopy.

The oxidation of spermidine or homospermidine with bovine serum amine oxidase (BSAO) was monitored in situ, using proton nuclear magnetic resonance spectroscopy in water with 10% D(2)O. NMR assignments were performed by spin decoupling and COSY spectra or by comparison with data from synthetic aminoaldehydes. The results represent the first in situ characterisation of the highly reactive aminoaldehydes and showed oxidation at the N(1) amino group of spermidine and homospermidine. Comparison of homospermidine with a variety of substrates revealed that among straight chain di- and polyamines both an aminopropyl group and two primary amino groups separated by seven (norspermidine) or eight (spermidine) carbon atoms were required for optimal substrate ability. However, highest activity was seen with the substrate N-(4-aminobutyl)hexahydropyrimidine, showing that the substrate channel of BSAO has a dual substrate preference, with moderately bulky substituents at the distal end of a diamine contributing equally well as an alkyl amino group. Cytotoxic investigations of a variety of substrates for BSAO, confirmed previous results, that cytotoxicity is primarily linked to polyamines encompassing the aminopropyl moiety. No acrolein was observed at any time during the oxidation showing that it reacts very fast with available amino groups forming a variety of derivatives.

Aldehydes↗
PubMed2005

Discovery of new natural products by application of X-hitting, a novel algorithm for automated comparison of full UV spectra, combined with structural determination by NMR spectroscopy.

X-hitting, a newly developed algorithm for automated comparison of UV data, has been used for the tracking of two novel spiro-quinazoline metabolites, lapatins A (1) and B (2), in a screening study targeting quinazolines. The structures of 1 and 2 were elucidated by analysis of spectroscopic data, primarily 2D NMR.

Algorithms↗
PubMed2004

Two novel types of O-glycans on the mugwort pollen allergen Art v 1 and their role in antibody binding.

Art v 1, the major allergen of mugwort (Artemisia vulgaris) pollen contains galactose and arabinose. As the sera of some allergic patients react with natural but not with recombinant Art v 1 produced in bacteria, the glycosylation of Art v 1 may play a role in IgE binding and human allergic reactions. Chemical and enzymatic degradation, mass spectrometry, and 800 MHz (1)H and (13)C nuclear magnetic resonance spectroscopy indicated the proline-rich domain to be glycosylated in two ways. We found a large hydroxyproline-linked arabinogalactan composed of a short beta1,6-galactan core, which is substituted by a variable number (5-28) of alpha-arabinofuranose residues, which form branched side chains with 5-, 2,5-, 3,5-, and 2,3,5-substituted arabinoses. Thus, the design of the Art v 1 polysaccharide differs from that of the well known type II arabinogalactans, and we suggest it be named type III arabinogalactan. The other type of glycosylation was formed by single (but adjacent) beta-arabinofuranoses linked to hydroxyproline. In contrast to the arabinosylation of Ser-Hyp(4) motifs in other hydroxyproline-rich glycoproteins, such as extensins or solanaceous lectins, no oligo-arabinosides were found in Art v 1. Art v 1 and parts thereof produced by alkaline degradation, chemical deglycosylation, proteolytic degradation, and/or digestion with alpha-arabinofuranosidase were used in enzyme-linked immunosorbent assay and immunoblot experiments with rabbit serum and with the sera of patients. Although we could not observe antibody binding by the polysaccharide, the single hydroxyproline-linked beta-arabinose residues appeared to react with the antibodies. Mono-beta-arabinosylated hydroxyproline residues thus constitute a new, potentially cross-reactive, carbohydrate determinant in plant proteins.

Allergens↗
PubMed2004

The structure of the glucuronoxylomannan produced by culinary-medicinal yellow brain mushroom (Tremella mesenterica Ritz.:Fr., Heterobasidiomycetes) grown as one cell biomass in submerged culture.

The yellow brain mushroom Tremella mesenterica possesses a wide spectrum of medicinal properties, including immunostimulating, protecting against radiation, antidiabetic, anti-inflammatory, hypocholesterolemic, hepatoprotective, and antiallergic effects. A unique feature of T. mesenterica is that most of the above mentioned medicinal properties depend on glucuronoxylomannan (GXM) contained in fruiting bodies or produced in pure culture conditions. We developed a new strain of T. mesenterica CBS 101939, which grows in submerged culture and offers superior yields of one-cell biomass rich in exocellular heteropolysaccharide GXM. The structure of the GXM was analyzed by NMR spectroscopy and chemical methods. The polysaccharide has a defined repeating unit structure, which is O-acetylated at several points: [structure: see text]. These results differ from previously published structure of Tremella extracellular polysaccharides, where mannan backbone was believed to be randomly glycosylated with xylan chains of different length.

Agaricales↗
PubMed2004

Oligosaccharides implicated in recognition are predicted to have relatively ordered structures.

Fucosylated O- and N-linked glycans are essential recognition molecules in plants and animals. To understand how they impart their functions, through interactions with proteins, requires a detailed analysis of structure and dynamics, but this is presently lacking. In this study, the three-dimensional structure and dynamics of three fucosylated oligosaccharides are investigated using a combination of high field (800 MHz) nuclear magnetic resonance and long (50 ns) molecular dynamics simulations in explicit water. Predictions from dynamics simulations were in agreement with nuclear Overhauser cross-peak intensities. Similarly, a theory of weak alignment in neutral media resulted in reasonable predictions of residual dipolar couplings for the trisaccharide fucosyllactose. However, for larger penta- and hexasaccharides (LNF-1 and LND-1), the anisotropic component of the alignment was underestimated, attributed to shape irregularities of the fucosyl branches on an otherwise linear core, being more pronounced in a singly branched than a doubly branched oligosaccharide. Simulations, confirmed by experiment, predicted fucosylated molecules that are restricted to librations about a single average conformation. This restriction is partly due to microscopic water interactions, which act to stabilize intramolecular hydrogen bonds and maintain tight and ordered conformations; a view not forthcoming from simpler, nonaqueous simulations. Such a conclusion is crucial for understanding how these molecules interact with proteins and impart their recognition properties.

Carbohydrate Conformation↗
PubMed2003

The structure of the polysaccharide part of the LPS from Serratia marcescens serotype O19, including linkage region to the core and the residue at the non-reducing end.

The structure of the LPS from Serratia marcescens serotype O19 was investigated. Deamination of the LPS released the O-chain polysaccharide together with a fragment of the core oligosaccharide. The following structure of the product was determined by NMR spectroscopy, mass spectrometry, and chemical methods: [carbohydrate structure: see text] The main polymer consists of a repeating disaccharide V-U and is present on average of 18 units per chain as estimated by integration of signals in the NMR spectra. The residue O corresponds to the primer, which initiates biosynthesis of the O-chain, and an oligomer of a disaccharide R-S is an insert between the primer and the main polymer. The polysaccharide has a beta-Kdo residue at the non-reducing end, a feature similar to that observed previously in the LPS from Klebsiella O12.

Carbohydrate Sequence↗
PubMed2003

Detection of 3-hydroxykynurenine in a plant pathogenic fungus.

A redox-active compound has been purified from the barley powdery mildew fungus Blumeria ( Erysiphe ) graminis f. sp. hordei. A combination of spectrophotometry, MS and NMR has identified it as 3-hydroxykynurenine (3OHKyn). This compound, never previously detected in any fungus or pathogen, is best known for its role in vertebrate cataracts. It is found abundantly in developing and germinating spores and also in runner hyphae. Two roles for 3OHKyn are discussed: first, the presence of active oxygen species would enable 3OHKyn to cross-link the spore chemically with the plant. Secondly, it may be acting as an UV protectant and an antioxidant.

Ascomycota↗
PubMed2003

Structure of the exceptionally large nonrepetitive carbohydrate backbone of the lipopolysaccharide of Pectinatus frisingensis strain VTT E-82164.

The structures of the oligosaccharides obtained after acetic acid hydrolysis and alkaline deacylation of the rough-type lipopolysaccharide (LPS) from Pectinatus frisingensis strain VTT E-82164 were analysed using NMR spectroscopy, MS and chemical methods. The LPS contains two major structural variants, differing by a decasaccharide fragment, and some minor variants lacking the terminal glucose residue. The largest structure of the carbohydrate backbone of the LPS that could be deduced from experimental results consists of 25 monosaccharides (including the previously found Ara4NP residue in lipid A) arranged in a well-defined nonrepetitive structure: We presume that the shorter variant with R1 = H represents the core-lipid A part of the LPS, and the additional fragment is present instead of the O-specific polysaccharide. Structures of this type have not been previously described. Analysis of the deacylation products obtained from the LPS of the smooth strain, VTT E-79100T, showed that it contains a very similar core but with one different glycosidic linkage.

Acetic Acid↗
PubMed2002

Structures of lipopolysaccharides from Klebsiella pneumoniae. Eluicidation of the structure of the linkage region between core and polysaccharide O chain and identification of the residues at the non-reducing termini of the O chains.

Deamination of LPSs from Klebsiella pneumoniae released O-chain polysaccharides together with a fragment of the core oligosaccharide. The structures of the products from serotypes O1, O2a, O2a,c, O3, O4, O5, and O12 were determined by NMR spectroscopy and chemical methods, identifying the linkage region between the O antigens and the core as well as novel residues at the non-reducing ends of the polysaccharides. All serotypes had an identical linkage between the O chain and core.

Carbohydrate Conformation↗
PubMed2002

NMR and MS evidences for a random assembled O-specific chain structure in the LPS of the bacterium Xanthomonas campestris pv. Vitians. A case of unsystematic biosynthetic polymerization.

Xanthomonas campestris pv. vitians is a Gram-negative plant-associated bacterium that acts as causative agent of bacterial leaf spot and headrot in lettuce. The lipopolysaccharide of this bacterium is suspected to be an important molecule for adhesion to and infection of the plants. The lipopolysaccharide has been isolated from the phenol phase and the O-specific chain characterized by compositional analysis, high field NMR and MALDI-TOF MS. It consists of a nonrepetitive branched polysaccharide with a rhamnan backbone to which Fuc3NAc is linked. The NMR and MS approach led to the characterization of the fine structure of the polymer, which is randomly assembled. The rhamnan backbone is built up of beta-Rhap and alpha-Rhap, this last is present in one, two or three adjacent units and branched by an alpha-Fucp3NAc unit. This is a real case of a random constituted O-specific chain, therefore biosynthetic studies towards the comprehension of this irregular biosynthesis are needed.

Carbohydrate Conformation↗