The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Desana Lišková - One of the best experts on this subject based on the ideXlab platform.
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galactoglucomannan oligosaccharides alleviate cadmium stress in arabidopsis
Journal of Plant Physiology, 2014Co-Authors: Danica Kucerova, Karin Kollarova, Ivan Zelko, Zuzana Vatehova, Desana LiškováAbstract:Summary Our study focused on the mediatory role of galactoglucomannan oligosaccharides (GGMOs) in plant protection against cadmium stress, examined mainly on the primary root growth of Arabidopsis thaliana . The application of GGMOs diminished the negative effect of cadmium on root length, root growth dynamics and also on photosynthetic pigment content. We tested the hypothesis that the effect of GGMOs is associated with decreased cadmium accumulation or its modified distribution. Cadmium distribution was observed chronologically from the first day of plant culture and depended on the duration of cadmium treatment. First, cadmium was stored in the root and hypocotyl and later transported by xylem to the leaves and stored there in trichomes. The protective effect of GGMOs was not based on modified cadmium distribution or its decreased accumulation. In cadmium and GGMOs + cadmium-treated plants, the formation of suberin lamellae was shifted closer to the root apex compared to the control and GGMOs. No significant changes between cadmium and GGMOs + cadmium variants in suberin lamellae development corresponded with any differences in cadmium uptake. GGMOs also stimulated Arabidopsis root growth under non-stress conditions. In this case, suberin lamellae were developed more distantly from the root apex in comparison with the control. Faster solute and water transport could explain the faster plant growth induced by GGMOs. Our results suggest that, in cadmium-stressed plants, GGMOs’ protective action is associated with the response at the metabolic level.
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Galactoglucomannan oligosaccharides are assumed to affect tracheary element formation via interaction with auxin in Zinnia xylogenic cell culture
Plant Cell Reports, 2013Co-Authors: Anna Kakosova, Deborah Goffner, Catherine Digonnet, Desana LiškováAbstract:Key message Galactoglucomannan oligosaccharides seem to interact with auxin in xylogenic cell culture, thus influencing mainly metaxylem-like tracheary element differentiation depending on timing with hormones and the process kinetics. Abstract Complex mapping of Zinnia mesophyll cell transdifferentiation into tracheary elements with or without prior cell division was documented after palisade and spongy parenchyma cell immobilization during the first 4 days of culture. Here, we report a positive effect of galactoglucomannan oligosaccharides on cell viability and density and higher metaxylem-like tracheary element formation in xylogenic cell culture. The maximal positive effect was achieved by the simultaneous addition of the oligosaccharides and growth hormones (auxin, cytokinin) to the cell culture medium. Moreover, a large number of metaxylem-like tracheary elements were observed in a low-auxin medium supplemented with oligosaccharides, but not in a low-cytokinin medium, suggesting a close relationship between auxin and the oligosaccharides during tracheary element formation.
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galactoglucomannan oligosaccharides are assumed to affect tracheary element formation via interaction with auxin in zinnia xylogenic cell culture
Plant Cell Reports, 2013Co-Authors: Anna Kakosova, Deborah Goffner, Catherine Digonnet, Desana LiškováAbstract:Key message Galactoglucomannan oligosaccharides seem to interact with auxin in xylogenic cell culture, thus influencing mainly metaxylem-like tracheary element differentiation depending on timing with hormones and the process kinetics.
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further biological characteristics of galactoglucomannan oligosaccharides
Biologia Plantarum, 2006Co-Authors: Karin Kollarova, Desana Lišková, Peter CapekAbstract:The biological activity of cell wall-derived galactoglucomannan oligosaccharides (GGMOs) was dependent on their chemical structure. Galactosyl side chains linked to the glucomanno-core influenced their inhibition of elongation growth of pea (Pisum sativum L. cv. Tyrkys) stem segments induced by 2,4-dichlorophenoxyacetic acid (2,4-D). Reduction of the number of galactosyl side chains in GGMOs caused stimulation of the endogenous growth. Modification on the glucomanno-reducing end did not affect significantly the activity of these oligosaccharides. GGMOs inhibited also the elongation induced by indole-3-acetic acid (IAA) and gibberellic acid (GA3). In the presence of IAA the elongation growth was inhibited to 20 – 35 % after 24 h of incubation depending on GGMOs concentrations (1 μM, 10 nM, 0.1 nM), similarly as in the presence of 2,4-D, which confirms the hypothesis of GGMOs antiauxin properties. The elongation induced by GA3 was inhibited to 25 – 60 %, however, the time course of inhibition was different compared with IAA and 2,4-D. The highest inhibition was determined already after 6 h of incubation with a significant decrease after this time. The results indicated a competition between GGMOs and growth regulators.
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galactoglucomannan from the secondary cell wall of picea abies l karst
Carbohydrate Research, 2000Co-Authors: Peter Capek, Marta Kubackova, Juraj Alfoldi, Ladislav Bilisics, Desana Lišková, D. KákoniováAbstract:Abstract The fine structural features of alkali-extracted galactoglucomannan composed of d -galactose, d -glucose and d -mannose in a 1:8:33 mol 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 1 H and 13 C NMR measurements of the polymer and products of partial acid hydrolysis confirmed a β-(1→4)-linked backbone of galactoglucomannan containing the segments of mannosyl residues (Man 2 , Man 3 , Man 4 , etc.) interrupted with the segments having both mannose and glucose residues, as well as the segments in which d -Glc p units can be adjacent to each other (Glc 2 ). Further, the low content of branching points (∼3%) at the positions of O-6, O-3 and O-2 of mannosyl and O-6 and O-3 of glucosyl residues, but preferably of mannosyl ones, indicates the presence of short side-chains terminated at position O-6 predominantly by d -galactose units as single stubs.
Stefan Willför - One of the best experts on this subject based on the ideXlab platform.
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Optimization of the extraction of Galactoglucomannans from Pinus halepensis
Holzforschung, 2020Co-Authors: Nacera Benouadah, Andrey Pranovich, Djamel Aliouche, Jalel Labidi, Stefan WillförAbstract:Abstract The effectiveness of pressurized hot-water extraction conditions for obtaining Galactoglucomannans (GGMs) from Pinus halepensis suitable for applications like coatings and films packaging was investigated. For this purpose, high molar masses with high yields are required, presenting a serious challenge for hot-water extraction processes. The extraction of GGMs was carried out in an accelerated solvent extractor (ASE) and the isolation was performed by precipitation in ethanol. Three temperatures in the range 160–180 °C and five extraction times 5–90 min were tested in order to optimize extraction parameters of GGMs, avoiding thermal and chemical degradation in hot-water. Total dissolved solids (TDS) were determined gravimetrically after freeze-drying and weight average molar masses (Mw) were determined by high-performance size exclusion chromatography (HPSEC). Total non-cellulosic carbohydrates were determined by gas chromatography (GC) after acid methanolysis. Free monomers were additionally analyzed by GC. Lignin in water extracts was measured by an ultraviolet (UV) method. Acetic acid was determined after alkaline hydrolysis of acetyl groups and analyzed by HPSEC. The main parameters influencing the extraction processes of the GGMs, namely, extraction time and temperature were studied. Optimal extraction parameters of GGMs were identified at 170 °C and 20 min extraction time, with average Mw of extracted fraction of 7 kDa leading to a GGM yield of approximately 56 mg g o . d . m − 1 ${\text{mgg}}_{\text{o}.\text{d}.\text{m}}^{-1}$ , corresponding to 6% on dry wood basis.
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O-acetyl galactoglucomannan esters for barrier coatings
Cellulose, 2014Co-Authors: Victor Kisonen, Chunlin Xu, Jonas Hartman, Roger Bollström, Hille Rautkoski, Maristiina Nurmi, Patrik Eklund, Jarl Hemming, Stefan WillförAbstract:A major enhancement of grease and water vapor barrier properties was accomplished with a 1–10 g/m^2 coating of O -acetyl galactoglucomannan (GGM) ester or with GGM coatings applied as water dispersions on cartonboard. GGMs were esterified with phthalic and benzoic anhydrides, respectively. The novel phthalic esters of GGM (GGM-Ph) were characterized with HPLC, NMR, and matrix-assisted laser desorption/ionization with mass spectrometry (MALDI-TOF-MS). The degree of substitution of GGM-Ph was obtained by ^1H NMR, ^13C NMR, and HPLC. The GGM esters and GGM were coated onto cartonboard, and they demonstrated good moisture and very good grease resistance even with thin 1–3 g/m^2 coatings. The time for penetration of 0.1 % rapeseed oil was 54 h with the 2.4 g/m^2 coating thickness. The lowest water vapor transmission value was 39 g/m^2/24 h with 9.7 g/m^2 coating. The GGM esters had clearly higher water resistance and slightly higher grease barrier values than native GGM. High-molar-mass-based GGM (50 kg/mol) and GGM-Ph rendered better water vapor and grease barrier properties than low-molar-mass GGM (9 kg/mol) and GGM-Ph. The GGM-based coatings can be safely used on an industrial scale as water was used as a solvent. As obtained from non-food-based side-stream wood-based resources, GGM and GGM esters project a sustainable and modern conception for barrier purposes in food packaging.
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Modification of nanofibrillated cellulose using amphiphilic block-structured Galactoglucomannans
Carbohydrate Polymers, 2014Co-Authors: Alina Lozhechnikova, Chunlin Xu, Stefan Willför, Jari Vartiainen, Monika ÖsterbergAbstract:Nanofibrillated cellulose (NFC) and hemicelluloses have shown to be highly promising renewable components both as barrier materials and in novel biocomposites. However, the hydrophilic nature of these materials restricts their use in some applications. In this work, the usability of modified O-acetyl galactoglucomannan (GGM) for modification of NFC surface properties was studied. Four GGM-block-structured, amphiphilic derivatives were synthesized using either fatty acids or polydimethylsiloxane as hydrophobic tails. The adsorption of these GGM derivatives was consecutively examined in aqueous solution using a quartz crystal microbalance with dissipation monitoring (QCM-D). It was found that the hydrophobic tails did not hinder adsorption of the GGM derivatives to cellulose, which was concluded to be due to the presence of the native GGM-block with high affinity to cellulose. The layer properties of the adsorbed block-co-polymers were discussed and evaluated. Self-standing NFC films were further prepared and coated with the GGM derivatives and the effect of the surface modification on wetting properties and oxygen permeability (OP) of the modified films was assessed.
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synthesis of novel cationic hydrogels from spruce o acetyl galactoglucomannan for metal ion removal
247th National Spring Meeting of the American-Chemical-Society (ACS) MAR 16-20 2014 Dallas TX, 2014Co-Authors: Maria Soledad Chavez Bastidas, Chunlin Xu, Julio Antonio Sanchez Poblete, Regis Teixeira Mendonça, Stefan WillförAbstract:Synthesis of novel cationic hydrogels from spruce O-acetyl galactoglucomannan for metal ion removal
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Cationised O-acetyl Galactoglucomannans: synthesis and characterisation.
Carbohydrate Polymers, 2013Co-Authors: Victor Kisonen, Andrey Pranovich, Chunlin Xu, Hanna Lindqvist, Patrik Eklund, Anna Sundberg, Jari Sinkkonen, Francisco Vilaplana, Stefan WillförAbstract:Water-soluble O-acetyl-Galactoglucomannans (GGMs) can be obtained from Norway spruce by hot-water-extraction of the wood or as a side product by ultrafiltration of mechanical pulping waters. Cationic and amphiphilic polysaccharides and their derivatives are of interest for a number of applications and thus quaternary nitrogen moieties with cationic charge were grafted onto GGMs in the heterogeneous reaction to render a cationic polyelectrolyte. The degree of substitution was measured by elemental analysis of nitrogen, by quantitative 13C NMR and interestingly also by polyelectrolyte titration and the results were congruent. NMR, matrix-assisted laser desorption/ionisation mass spectroscopy (MALDI-TOF-MS), and FT-IR analysis were used to characterise the product. THF or DMSO with water enhanced the reaction efficiency and decreased Mw reduction in comparison to plain water as a reaction media. Cationised GGM was also successfully acetylated. The cationic derivatives of hemicelluloses can potentially be utilised as polyelectrolyte layers in packaging and pharmaceutical applications.
Marcello Iacomini - One of the best experts on this subject based on the ideXlab platform.
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Galactomannoglucans of lichenized fungi of Cladonia spp.: significance as chemotypes
FEMS microbiology letters, 1999Co-Authors: Sandra M. Woranovicz-barreira, Philip A J Gorin, PatrÃcia Lanzi Sassaki, Marcelo Pinto Marcelli, Marcello IacominiAbstract:Abstract The chemical structures of the glucans, Galactoglucomannans and galactomannoglucans of two species of the Cladonia , section Cocciferae , Cladonia miniata and Cladonia salmonea , were determined and compared. α- D -Glucans of the nigeran type were isolated from both species, in common with all Cladonia spp., along with Galactoglucomannans containing (1→6)-linked main-chains of α- D -Man p units substituted by structurally different and typical side-chains. Isolated were previously unreported galactomannoglucans, with (1→3)-linked main-chains of β- D -Glc p units, substituted at O -2,6 by side-chains. These consisted of β- D -Gal f , 6- O -substituted β- D -Gal f and 2- O -, 4- O -, 6- O - and 2,3-di- O -substituted α- D -Man p units. According to 13 C NMR spectroscopy, a similar galactomannoglucan was isolated from the Cladonia spp. Cladonia signata, Cladonia crispatula, Cladonia penicillata, Cladonia imperialis, Cladonia clathrata, Cladonia connexa, Cladonia substellata and Cladonia ibitipocae . Its presence could also contribute to the classic taxonomy of lichenized fungi.
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Novel structures in Galactoglucomannans of the lichens Cladonia substellata and Cladonia ibitipocae: significance as chemotypes
Phytochemistry, 1999Co-Authors: Sandra M Woranovicz, B. Mario Pinto, Philip A J Gorin, Marcello IacominiAbstract:Abstract The Galactoglucomannans of two species of the lichen genus Cladonia, C. substellata and C. ibitipocae, were compared. They were homogeneous on gel-filtration chromatography and structurally related, having (1→6)-linked α- d -mannopyranosyl main-chains, but were substituted in different patterns by α- and β- d -galacto-, β- d -gluco- and α- d -mannopyranosyl groups. The C-1 portions of their 13 C -NMR spectra are typical of the lichen species and indicate differences between the two polysaccharides. Partial acetolysis of the galactoglucomannan from C. substellata gave rise to oligosaccharides and three were identified, namely α- d -Manp-(1→3)-αβ- d -Galp, α- d -Manp-(1→2)-αβ- d -Manp and α- d -Manp-(1→2)-[β- d -Glcp-(1→4)]-αβ- d -Manp, whereas only the latter two were obtained from that of C ibitipocae. Methylation and Smith degradation data confirmed these results. Whereas the mannobiose represents a common structure in lichen heteropolysaccharides, it is the first time that the other oligosaccharides have been isolated from those of lichens.
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Novel structures in Galactoglucomannans of the lichens Cladonia substellata and Cladonia ibitipocae: significance as chemotypes
Phytochemistry, 1999Co-Authors: Sandra M Woranovicz, B. Mario Pinto, Philip A J Gorin, Marcello IacominiAbstract:The Galactoglucomannans of two species of the lichen genus Cladonia, C. substellata and C. ibitipocae, were compared. They were homogeneous on gel-filtration chromatography and structurally related, having (1-->6)-linked alpha-D-mannopyranosyl main-chains, but were substituted in different patterns by alpha- and beta-D-galacto-, beta-D-gluco- and alpha-D-mannopyranosyl groups. The C-1 portions of their 13C-NMR spectra are typical of the lichen species and indicate differences between the two polysaccharides. Partial acetolysis of the galactoglucomannan from C. substellata gave rise to oligosaccharides and three were identified, namely alpha-D-Manp-(1-->3)-alpha beta-D-Galp, alpha-D-Manp-(1-->2)-alpha beta-D-Manp and alpha-D-Manp-(1-->2)-[beta-D-Glcp-(1-->4)]-alpha beta-D-Manp, whereas only the latter two were obtained from that of C ibitipocae. Methylation and Smith degradation data confirmed these results. Whereas the mannobiose represents a common structure in lichen heteropolysaccharides, it is the first time that the other oligosaccharides have been isolated from those of lichens.
Paul Dupree - One of the best experts on this subject based on the ideXlab platform.
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Molecular architecture of softwood revealed by solid-state NMR
Nature Communications, 2019Co-Authors: Oliver M. Terrett, Jan J. Lyczakowski, W. Trent Franks, Dinu Iuga, Steven P Brown, R. Dupree, Li Yu, Paul DupreeAbstract:Economically important softwood from conifers is mainly composed of the polysaccharides cellulose, galactoglucomannan and xylan, and the phenolic polymer, lignin. The interactions between these polymers lead to wood mechanical strength and must be overcome in biorefining. Here, we use ^13C multidimensional solid-state NMR to analyse the polymer interactions in never-dried cell walls of the softwood, spruce. In contrast to some earlier softwood cell wall models, most of the xylan binds to cellulose in the two-fold screw conformation. Moreover, galactoglucomannan alters its conformation by intimately binding to the surface of cellulose microfibrils in a semi-crystalline fashion. Some galactoglucomannan and xylan bind to the same cellulose microfibrils, and lignin is associated with both of these cellulose-bound polysaccharides. We propose a model of softwood molecular architecture which explains the origin of the different cellulose environments observed in the NMR experiments. Our model will assist strategies for improving wood usage in a sustainable bioeconomy.Understanding the interactions between the constituents of the cell walls in wood is important for understanding the mechanical properties. Here, the authors report on a solid-state NMR study of never-dried softwood, noticing differences to previous reports and develop a model of softwood architecture.
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Molecular architecture of softwood revealed by solid-state NMR
Nature communications, 2019Co-Authors: Oliver M. Terrett, Jan J. Lyczakowski, W. Trent Franks, Dinu Iuga, Steven P Brown, R. Dupree, Paul DupreeAbstract:Economically important softwood from conifers is mainly composed of the polysaccharides cellulose, galactoglucomannan and xylan, and the phenolic polymer, lignin. The interactions between these polymers lead to wood mechanical strength and must be overcome in biorefining. Here, we use 13C multidimensional solid-state NMR to analyse the polymer interactions in never-dried cell walls of the softwood, spruce. In contrast to some earlier softwood cell wall models, most of the xylan binds to cellulose in the two-fold screw conformation. Moreover, galactoglucomannan alters its conformation by intimately binding to the surface of cellulose microfibrils in a semi-crystalline fashion. Some galactoglucomannan and xylan bind to the same cellulose microfibrils, and lignin is associated with both of these cellulose-bound polysaccharides. We propose a model of softwood molecular architecture which explains the origin of the different cellulose environments observed in the NMR experiments. Our model will assist strategies for improving wood usage in a sustainable bioeconomy.
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the patterned structure of galactoglucomannan suggests it may bind to cellulose in seed mucilage
Plant Physiology, 2018Co-Authors: Li Yu, Jan J. Lyczakowski, Toshihisa Kotake, Soren Mogelsvang, Xiaolan Yu, Caroline S. Pereira, Munir S. Skaf, An Li, Paul DupreeAbstract:The interaction between mannan polysaccharides and cellulose microfibrils contributes to cell wall properties in some vascular plants, but the molecular arrangement of mannan in the cell wall and the nature of the molecular bonding between mannan and cellulose remain unknown. Previous studies have shown that mannan is important in maintaining Arabidopsis (Arabidopsis thaliana) seed mucilage architecture, and that Cellulose Synthase-Like A2 (CSLA2) synthesizes a glucomannan backbone, which Mannan α-Galactosyl Transferase1 (MAGT1/GlycosylTransferase-Like6/Mucilage Related10) might decorate with single α-Gal branches. Here, we investigated the ratio and sequence of Man and Glc and the arrangement of Gal residues in Arabidopsis mucilage mannan using enzyme sequential digestion, carbohydrate gel electrophoresis, and mass spectrometry. We found that seed mucilage galactoglucomannan has a backbone consisting of the repeating disaccharide [4)-β-Glc-(1,4)-β-Man-(1,], and most of the Man residues in the backbone are substituted by single α-1,6-Gal. CSLA2 is responsible for the synthesis of this patterned glucomannan backbone and MAGT1 catalyses the addition of α-Gal. In vitro activity assays revealed that MAGT1 transferred α-Gal from UDP-Gal only to Man residues within the CSLA2 patterned glucomannan backbone acceptor. These results indicate that CSLAs and galactosyltransferases are able to make precisely defined galactoglucomannan structures. Molecular dynamics simulations suggested this patterned galactoglucomannan is able to bind stably to some hydrophilic faces and to hydrophobic faces of cellulose microfibrils. A specialization of the biosynthetic machinery to make galactoglucomannan with a patterned structure may therefore regulate the mode of binding of this hemicellulose to cellulose fibrils.
Maija Tenkanen - One of the best experts on this subject based on the ideXlab platform.
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Colloidal features of softwood Galactoglucomannans-rich extract.
Carbohydrate polymers, 2020Co-Authors: Mamata Bhattarai, Leena Pitkänen, Maija Tenkanen, Irina Sulaeva, Inkeri Kontro, Antje Potthast, Kirsi S MikkonenAbstract:Abstract Development of a sustainable bioeconomy requires valorization of renewable resources, such as wood hemicelluloses. The intra- and inter-molecular association of hemicelluloses within themselves or with other wood components can result in complex macromolecular features. These features exhibit functionality as hydrocolloids, however macromolecular characterization of these heterogeneous materials are challenging using conventional techniques such as size-exclusion chromatography. We studied Galactoglucomannans (GGM) -rich softwood extracts at two grades of purity—as crude extract and after ethanol-precipitation. Asymmetrical flow field-flow fractionation (AF4) was optimized and utilized to fractionate size classes in GGM extracts, and subsequent characterization was performed with light scattering and microscopy techniques. Both GGM extracts contained polysaccharides of around 10,000 g/mol molar mass, and colloidal assemblies and/or particles in sub-micron size range. The optimized AF4 method facilitates the characterization of complex biomass-derived carbohydrates without pre-fractionation, and provides valuable understanding of their unique macromolecular features for their future application in food, pharmaceuticals, and cosmetics.
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Influence of a family 29 carbohydrate binding module on the activity of galactose oxidase from Fusarium graminearum
Biochimica et Biophysica Acta - General Subjects, 2016Co-Authors: Filip Mollerup, THANH VINH VUONG, Kirsti Parikka, Maija Tenkanen, Emma MasterAbstract:Background Galactose oxidase (GaO) selectively oxidizes the primary hydroxyl of galactose to a carbonyl, facilitating targeted chemical derivatization of galactose-containing polysaccharides, leading to renewable polymers with tailored physical and chemical properties. Here we investigate the impact of a family 29 glucomannan binding module on the activity and binding of GaO towards various polysaccharides. Specifically, CBM29-1-2 from Piromyces equi was separately linked to the N- and C-termini of GaO. Results Both GaO-CBM29 and CBM29-GaO were successfully expressed in Pichia pastoris, and demonstrated enhanced binding to galactomannan, galactoglucomannan and galactoxyloglucan. The position of the CBM29 fusion affected the enzyme function. Particularly, C-terminal fusion led to greatest increases in galactomannan binding and catalytic efficiency, where relative to wild-type GaO, kcat/Km values increased by 7.5 and 19.8 times on guar galactomannan and locust bean galactomannan, respectively. The fusion of CBM29 also induced oligomerization of GaO-CBM29. Major conclusions Similar to impacts of cellulose-binding modules associated with cellulolytic enzymes, increased substrate binding impeded the action of GaO fusions on more concentrated preparations of galactomannan, galactoglucomannan and galactoxyloglucan; this was especially true for GaO-CBM29. Given the N-terminal positioning of the native galactose-binding CBM32 in GaO, the varying impacts of N-terminal versus C-terminal fusion of CBM29-1-2 may reflect competing action of neighboring CBMs. General significance This study thoroughly examines and discusses the effects of CBM fusion to non-lignocellulytic enzymes on soluble polysaccharides. Herein kinetics of GaO on galactose containing polysaccharides is presented for the first time.
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Films from Glyoxal-Crosslinked Spruce Galactoglucomannans Plasticized with Sorbitol
International Journal of Polymer Science, 2012Co-Authors: Kirsi S Mikkonen, Mari I Heikkila, Stefan Willför, Maija TenkanenAbstract:Films were prepared from a renewable and biodegradable forest biorefinery product, spruce O-acetyl-Galactoglucomannans (GGMs), crosslinked with glyoxal. For the first time, cohesive and self-standing films were obtained from GGM without the addition of polyol plasticizer. In addition, glyoxal-crosslinked films were prepared using sorbitol at 10, 20, 30, and 40% (wt.-% of GGM). Glyoxal clearly strengthened the GGM matrix, as detected by tensile testing and dynamic mechanical analysis. The elongation at break of films slightly increased, and Young's modulus decreased with increasing sorbitol content. Interestingly, the tensile strength of films was constant with the increased plasticizer content. The effect of sorbitol on water sorption and water vapor permeability (WVP) depended on relative humidity (RH). At low RH, the addition of sorbitol significantly decreased the WVP of films. The glyoxal-crosslinked GGM films containing 20% sorbitol exhibited the lowest oxygen permeability (OP) and WVP of the studied films and showed satisfactory mechanical performance.
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spruce galactoglucomannan films show promising barrier properties
Carbohydrate Polymers, 2010Co-Authors: Kirsi S Mikkonen, Mari I Heikkila, Harry Helen, Lea Hyvonen, Maija TenkanenAbstract:Films were prepared from sorbitol-plasticized spruce Galactoglucomannans (GGM), which are a potential new product from forest biorefineries. GGM were also mixed with konjac glucomannan (KGM), poly(vinyl alcohol) (PVOH), and cellulose nanowhiskers (CNW). Permeability properties of GGM-based films were compared to those of films from commercial mannans, namely KGM, guar gum galactomannan (GG), and locust bean gum galactomannan (LBG). GGM-based films had lower water vapor permeability than the films formed from any of the other mannans. The oxygen permeability of GGM films was of the same magnitude as that of commercial polyethylene/ethylene vinyl alcohol/polyethylene laminate film. The aroma permeability of GGM films was low. All films were transparent in the visible region, but GGM films blocked the light transmission in the ultraviolet region of the spectra.
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Oxidation of Polysaccharides by Galactose Oxidase
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Kirsti Parikka, Ann-sofie Leppänen, Leena Pitkänen, Markku Reunanen, Stefan Willför, Maija TenkanenAbstract:Galactose oxidase was used as a catalyst to oxidize selectively the C-6 hydroxyls of terminal galactose to carbonyl groups. The polysaccharides studied included spruce galactoglucomannan, guar galactomannan, larch arabinogalactan, corn fiber arabinoxylan, and tamarind seed xyloglucan, with terminal galactose contents varying from 6% to 40%. A multienzyme system was used, with catalase and horseradish peroxidase to enhance the action of galactose oxidase. An analysis technique was developed for the quantification of the reactive aldehydes with GC-MS, utilizing NaBD4 reduction and acidic methanolysis. The best oxidation degrees of terminal galactosyls were obtained with xyloglucan (85% of galactose) and spruce galactoglucomannan (65% of galactose). The highest oxidation degree based on total carbohydrates was achieved with guar gum (28%), which had the highest galactose content. The oxidation resulted in changes in the physicochemical properties of the polysaccharide solutions, and the changes observed vari...
