| 1. |
- Bankefors, Johan, et al.
(författare)
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A comparison of the metabolic profile on intact tissue and extracts of muscle and liver of juvenile Atlantic salmon (Salmo salar L.) - Application to a short feeding study
- 2011
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Ingår i: Food Chemistry. - : Elsevier BV. - 0308-8146 .- 1873-7072. ; 129, s. 1397-1405
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Tidskriftsartikel (refereegranskat)abstract
- The metabolite profiles from muscles and livers of Atlantic salmon were investigated using high resolution nuclear magnetic resonance (HR-NMR) spectroscopy of aqueous extracts and magic angle spinning (MAS) NMR spectroscopy of intact tissues. Comparison of the data showed that most small metabolites present in the aqueous extracts were also identified in the Carr-Purcell-Meiboom-Gill (CPMG) MAS NMR spectra of the intact tissues. Not only the total omega-3 fatty acid content, but also the EPA and DHA content, in the muscle and liver tissues could be calculated directly from the diffusion-edited MAS NMR spectra without the need for lipophilic extraction. The effect of replacing a normal fish meal during a period of 3 months with a diet containing 20% zygomycete was also investigated by multivariate analysis of the NMR spectra. Principal component analysis (PCA) was used to study the small metabolites distribution in the aqueous extracts of liver and muscles, and revealed that the feed containing zygomycete could have an influence on the metabolites profiles of juvenile Atlantic salmon. (C) 2011 Elsevier Ltd. All rights reserved.
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| 2. |
- Escalante, Alfredo, 1975, et al.
(författare)
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Flexible oxygen barrier films from spruce xylan
- 2012
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 87:4, s. 2381-2387
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Tidskriftsartikel (refereegranskat)abstract
- Arabinoglucuronoxylan was extracted from Norway spruce and films prepared by casting from aqueous solution. The sugar analysis and NMR confirmed that the spruce xylan was composed of arabinose, 4-O-methyl-glucuronic acid and xylose in a ratio of 1:2:11 respectively. Substitutions of 4-O-methyl-alpha-D-GlcpA at O-2 and of alpha-L-Araf at O-3 on the xylose backbone were found by NOE analysis. NOE cross-peaks indicated as well that there is at least one free xylose on the main chain present between two substitutions. Whether the distribution of side chains was random or in blocks was uncertain. The average molecular weight of the sample was determined by size exclusion chromatography to be 12,780 g/mol. Arabinoglucoronoxylan casting yielded transparent flexible films with an average stress at break of 55 MPa, strain at break of 2.7% and a Young's Modulus 2735 MPa. Wide-angle X-ray scattering analysis showed that the arabinoglucuronoxylan films were totally amorphous. Addition of sorbitol as plasticizer resulted in less strong but more flexible films (strain at break of 5%). Peaks of crystallinity could be seen in X-ray which corresponds to sorbitol crystallizing in distinct phases. The dynamic mechanical analysis showed that the arabinoglucuronoxylan film softened at a later relative humidity (80% RH) in comparison with plasticized films (60% RH). The films showed low oxygen permeability and thus have a potential application in food packaging.
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| 3. |
- Hao, Dong-Xia, et al.
(författare)
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Residue-level elucidation of the ligand-induced protein binding on phenyl-argarose microspheres by NMR hydrogen/deuterium exchange technique
- 2012
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 8:23, s. 6248-6255
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Tidskriftsartikel (refereegranskat)abstract
- Protein-ligand interactions on liquid-solid interfaces governed the design of functional biomaterials. However, accurate residue details of ligand induced protein binding and unfolding on an interface were still unknown by the current ensemble of protein structure characterizations. Here, a hydrogen/deuterium (H/D) approach coupled with analysis of NMR TOCSY spectra and the solvent accessible surface area (SASA) was designed to enable residue level understanding of lysozyme adsorbed at a phenyl-ligand modified surface. Results showed that the binding sites and unfolding of lysozyme molecules on phenyl-agarose microspheres demonstrated significant ligand-density dependence and protein-coverage dependence. Either increasing ligand density or decreasing adsorption coverage would lead to more binding sites and unfolding of the protein molecules. With the multipoint adsorption strengthening, the protein molecule changed from lying end-on to side-on. Finally, Molecular Dock simulation was utilized to evaluate the NMR determined binding sites based on energy ranking of the binding. It confirmed that this NMR approach represents a reliable route to in silico abundant residue-level structural information during protein interaction with biomaterials.
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| 4. |
- Lundqvist, Lena, et al.
(författare)
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Comparative Characterization of Two Marine Alginate Lyases from Zobellia galactanivorans Reveals Distinct Modes of Action and Exquisite Adaptation to Their Natural Substrate
- 2013
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 288, s. 23021-23037
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Tidskriftsartikel (refereegranskat)abstract
- Cell walls of brown algae are complex supramolecular assemblies containing various original, sulfated, and carboxylated polysaccharides. Among these, the major marine polysaccharide component, alginate, represents an important biomass that is successfully turned over by the heterotrophic marine bacteria. In the marine flavobacterium Zobellia galactanivorans, the catabolism and uptake of alginate are encoded by operon structures that resemble the typical Bacteroidetes polysaccharide utilization locus. The genome of Z. galactanivorans contains seven putative alginate lyase genes, five of which are localized within two clusters comprising additional carbohydrate-related genes. This study reports on the detailed biochemical and structural characterization of two of these. We demonstrate here that AlyA1(PL7) is an endolytic guluronate lyase, and AlyA5 cleaves unsaturated units, alpha-L-guluronate or beta-D-manuronate residues, at the nonreducing end of oligo-alginates in an exolytic fashion. Despite a common jelly roll-fold, these striking differences of the mode of action are explained by a distinct active site topology, an open cleft in AlyA1(PL7), whereas AlyA5 displays a pocket topology due to the presence of additional loops partially obstructing the catalytic groove. Finally, in contrast to PL7 alginate lyases from terrestrial bacteria, both enzymes proceed according to a calcium-dependent mechanism suggesting an exquisite adaptation to their natural substrate in the context of brown algal cell walls.
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| 5. |
- Lundqvist, Lena, et al.
(författare)
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Substrate specificity of the recombinant alginate lyase from the marine bacteria Pseudomonas alginovora
- 2012
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 352, s. 44-50
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Tidskriftsartikel (refereegranskat)abstract
- The gene coding for an alginate lyase from the marine bacteria Pseudomonas alginovora X017 was cloned and heterologously expressed in Escherichia coli strains. The protein was produced in inclusion bodies and the active form was obtained by applying a refolding protocol based upon dilution. The biochemical characterization was performed on the active, refolded form of the alginate lyase. The substrate specificity was monitored by NMR. The degradation products were size-fractioned by size exclusion chromatography. The fractions were subsequently analyzed by ESI-MS to determine the molecular weight of the compounds. The structures of the different oligosaccharides were then elucidated by NMR. The enzyme was shown to be only acting on M-M diads. No enzymatic hydrolysis occurred between M-MG, G-MM or G-MG blocks proving that the sequence accounting for the generated oligomers by enzymatic hydrolysis is M-MM. The unsaturated oligosaccharides produced by the alginate lyase were Delta M, Delta MM, Delta MMM, and DMMMM indicating that the minimum structure recognized by the enzyme is the M6 oligosaccharide. (C) 2012 Elsevier Ltd. All rights reserved.
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| 6. |
- Morssing Vilén, Eric, et al.
(författare)
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Application of diffusion-edited NMR spectroscopy for selective suppression of water signal in the determination of monomer composition in alginates
- 2010
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Annan publikation (refereegranskat)abstract
- Alginate, a structural polysaccharide in brown seaweeds, is a linear copolymer of 1-4 linked -D-Mannuronic acid (M) and 1-4 linked -L-Guluronic acid (G) residues. These residues are arranged in homopolymeric regions of M and G-blocks and regions of heteropolymeric MG-blocks. The chemical composition of alginates influences their physical properties, like gel properties and viscosity. Alginates are used in a vast range of industrial applications, many of which have different demand on the physical properties of the polysaccharide. Therefore it is of great importance to have methods, such as IR, Raman, nearIR and NMR, that accurately can determine the M/G-ratio. The viscosity of alginate samples is usually decreased by partial acid hydrolysis, which is time consuming and can possibly alter the sample. Instead samples of low concentration can be used. The drawback is that the residual water peak in the NMR spectrum is several orders of magnitude larger than the alginate signals so water suppression is needed. Commonly used techniques such as presaturation or pulse field gradient based techniques suffer from lack of specificity, and any other signals that overlap with the solvent peak will also be suppressed. These techniques have also been shown to alter the intensities of signals in NMR spectra of alginates [1], leading to significant errors in the calculation of the M/G-ratio. By using a diffusion-filtered NMR experiment the signal from water can be suppressed while retaining the signals of interest. This approach exploits the difference in translational diffusion between the larger, slowly diffusing, solute molecules and the smaller, faster diffusing, water molecules. Using this technique the monomer composition of alginate powders, covering a large range of M/G ratios and viscosities, has been determined. References [1] T. Salomonsen et al., Magnetic Resonance in Food Science, 12 (2009)
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| 7. |
- Morssing Vilén, Eric, et al.
(författare)
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Application of diffusion-edited NMR spectroscopy for selective suppression of water signal in the determination of monomer composition in alginates
- 2011
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Ingår i: Magnetic Resonance in Chemistry. - : Wiley. - 0749-1581 .- 1097-458X. ; 49, s. 584–591-
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Tidskriftsartikel (refereegranskat)abstract
- Alginate is a linear copolymer of 1-4 linked β-d-mannuronic acid (M) and 1-4 linked α-l-guluronic acid (G). The physical properties of these polysaccharides such as gel properties and viscosity are largely correlated to the monomer composition (M/G ratio), the sequence of the polymer and the molecular weight. Determination of the M/G ratio is therefore important and NMR spectroscopy is among the most common methods used to accurately obtain this ratio. Instead of using time consuming, possibly sample altering, acid hydrolysis to reduce the viscosity of the alginate sample prior to analysis, samples of low concentrations can be used. However, this results in a water peak in the NMR spectrum that is several orders of magnitude larger than the alginate signals and water suppression is required. In this article, a diffusion-edited NMR experiment that suppresses the water peak while retaining the signals of interest has been used to enable correct M/G ratio determination. This approach exploits the difference in translational diffusion between the larger alginate molecules and the smaller water molecules. Using this method, the monomer composition of 20 different alginate powders was determined. The diffusion parameters were optimized to allow measurement for samples covering a large range of M/G ratios and viscosities. Thus, such method should be useful for analyzing large numbers of unknown alginate samples using, for example, automation procedures
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| 8. |
- Morssing Vilén, Eric, et al.
(författare)
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NMR Study on Hydroxy Protons of kappa- and kappa/mu-Hybrid Carrageenan Oligosaccharides: Experimental Evidence of Hydrogen Bonding and Chemical Exchange Interactions in kappa/mu Oligosaccharides
- 2010
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 11, s. 3487-3494
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Tidskriftsartikel (refereegranskat)abstract
- The hydroxy protons of kappa- and kappa/mu-hybrid carrageenan oligosaccharides have been studied by NMR spectroscopy in 85% H(2)O/15% acetone-d(6). Hydration and hydrogen bonding interactions in di- (kappa), tetra- (kappa kappa), hexa (kappa kappa kappa), and octa- (kappa kappa kappa kappa) kappa-oligosaccharides and hexa- (kappa mu kappa), octa- (kappa mu mu kappa), and deca- (kappa mu mu mu kappa) kappa/mu-oligosaccharides have been investigated by measuring the chemical shifts, temperature coefficients, and chemical exchange of the hydroxy protons. These NMR parameters indicate that no strong and persistent intramolecular hydrogen bonds involving hydroxy protons stabilize the structure of kappa-carrageenan oligosaccharides in aqueous solution. In the kappa/mu-oligosaccharides, the presence of chemical exchange between OH3 of alpha-D-Gal-6-sulfate (D6S) and OH2 of beta-D-Gal-4-sulfate (G4S) across the beta-D-Gal-4-S-(1 -> 4)-alpha-D-Gal-6-S linkage reveals the existence of a weak hydrogen bond interaction between the two hydroxyl groups. The smaller temperature coefficients of OH2_D6S and OH3_D6S indicate reduced hydration, interpreted as spatial proximity to the 4-sulfate group and O5 ring oxygen of the neighboring G4S residues, respectively. These first experimental results on the conformation of kappa/mu-carrageenan oligosaccharides shine light on the potential role of "kinks" in the properties of the three-dimensional carrageenan gel network.
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| 9. |
- Morssing Vilén, Eric, et al.
(författare)
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NMR Study on the Interaction of Trehalose with Lactose and Its Effect on the Hydrogen Bond Interaction in Lactose
- 2013
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Ingår i: Molecules. - : MDPI AG. - 1420-3049. ; 18, s. 9735-9754
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Tidskriftsartikel (refereegranskat)abstract
- Trehalose, a well-known stress-protector of biomolecules, has been investigated for its effect on the mobility, hydration and hydrogen bond interaction of lactose using diffusion-ordered NMR spectroscopy and NMR of hydroxy protons. In ternary mixtures of trehalose, lactose and water, the two sugars have the same rate of diffusion. The chemical shifts, temperature coefficients, vicinal coupling constants and ROE of the hydroxy protons in trehalose, lactose and sucrose were measured for the disaccharides alone in water/acetone-d(6) solutions as well as in mixtures. The data indicated that addition of trehalose did not change significantly the strength of the hydrogen bond interaction between GlcOH3 and GalO5' in lactose. Small upfield shifts were however measured for all hydroxy protons when the sugar concentration was increased. The chemical shift of the GlcOH3 signal in lactose showed less change, attributed to the spatial proximity to GalO5'. Chemical exchange between hydroxy protons of lactose and trehalose was observed in the ROESY NMR spectra. Similar effects were observed with sucrose indicating no specific effect of trehalose at the concentrations investigated (73 to 763 mg/mL) and suggesting that it is the concentration of hydroxy groups more than the type of sugars which is guiding intermolecular interactions.
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| 10. |
- Nestor, Gustav, et al.
(författare)
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Experimental evidence of chemical exchange over the beta(1 -> 3) glycosidic linkage and hydrogen bonding involving hydroxy protons in hyaluronan oligosaccharides by NMR spectroscopy
- 2010
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Ingår i: Organic and Biomolecular Chemistry. - : Royal Society of Chemistry (RSC). - 1477-0520 .- 1477-0539. ; 8, s. 2795-2802
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Tidskriftsartikel (refereegranskat)abstract
- The hydroxy protons of unsaturated di-, tetra-, hexa- and octa-saccharides of hyaluronan (Delta HA(2), Delta HA(4), Delta HA(6) and Delta HA(8)) in 85% H(2)O/15% acetone-d(6) have been studied by NMR spectroscopy. The chemical shifts (delta), chemical shift differences (Delta delta), temperature coefficients (d delta/dT) and nuclear or rotating-frame Overhauser effects (NOEs or ROEs) of hydroxy protons were measured to gain insight into hydration, hydrogen bonds and flexibility of the HA structure. The NMR data give the first experimental evidence that weak hydrogen bonds exist between O(4)H of N-acetyl-D-glucosamine (GlcNAc) and O(5) of D-glucuronic acid (GlcA) across the beta(1 -> 3) glycosidic linkage and between O(3)H of GlcA and O(5) of GlcNAc across the beta(1 -> 4)-linkage. A chemical exchange was observed between O(4)H of GlcNAc and O(2)H of GlcA over the beta(1 -> 3)-linkage. The interaction could be mediated through water bridge(s) and thus contribute to the water-retaining ability of hyaluronan. In this study it was also demonstrated how the chemical shifts of exchangeable hydroxy or amide proton signals can be used to describe small structural and conformational perturbations within large oligosaccharides.
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