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  • 1.
    Araújo, Ana Catarina
    et al.
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Nakhai, Azadeh
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Ruda, M.
    Slättegård, R.
    Gatenholm, P.
    Brumer, Harry
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    A general route to xyloglucan-peptide conjugates for the activation of cellulose surfaces2012Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 354, s. 116-120Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cellulose is an attractive supporting matrix for diverse biotechnological applications, including chromatography, diagnostics, and tissue replacement/scaffolding, due to its renewable resource status, low cost, and low non-specific interaction with biomolecules. In an effort to expand the biofunctionality of cellulose materials, we present here a versatile method for the synthesis of xyloglucan-peptide conjugates that harness the strong xyloglucan-cellulose binding interaction for gentle surface modification. Xylogluco-oligosaccharide aminoalditols (XGO-NH 2) were coupled to both linear and cyclic peptides, which contained the endothelial cell epitope Arg-Gly-Asp, in a facile two-step approach employing diethyl squarate cross-linking. Subsequent xyloglucan endo-transglycosylase-mediated coupling of the resulting XGO-GRGDS (Gly-Arg-Gly-Asp-Ser) and XGO-c[RGDfK]-PEG-PEG (cyclo[Arg-Gly-Asp-(d-Phe)-Lys]-PEG-PEG; where PEG is 8-amino-3,6-dioxaoctanoic acid) conjugates into high molecular mass xyloglucan yielded xyloglucan-RGD peptide conjugates suitable for cellulose surface activation. Notably, use of XGO-squaramate as a readily accessible, versatile intermediate overcomes previous limitations of solid-phase synthetic approaches to XGO-peptide conjugates, and furthermore allows the method to be generalized to a wide variety of polypeptides and proteins, as well as diverse primary amino compounds.

  • 2.
    Bergenstråhle, Malin
    et al.
    Cornell University.
    Wohlert, Jakob
    Cornell University.
    Brady, John
    Cornell University.
    Himmel, Michael
    National Renewable Energy Laboratory.
    Simulation studies of the insolubility of cellulose2010Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 345, nr 14, s. 2060-2066Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Molecular dynamics simulations have been used to calculate the potentials of mean force for separating short cellooligomers in aqueous solution as a means of estimating the contributions of hydrophobic stacking and hydrogen bonding to the insolubility of crystalline cellulose. A series of four potential of mean force (pmf) calculations for glucose, cellobiose, cellotriose, and cellotetraose in aqueous solution were performed for situations in which the molecules were initially placed with their hydrophobic faces stacked against one another, and another for the cases where the molecules were initially placed adjacent to one another in a co-planar, hydrogen-bonded arrangement, as they would be in cellulose ID. From these calculations, it was found that hydrophobic association does indeed favor a crystal-like structure over solution, as might be expected. Somewhat more surprisingly, hydrogen bonding also favored the crystal packing, possibly in part because of the high entropic cost for hydrating glucose hydroxyl groups, which significantly restricts the configurational freedom of the hydrogen-bonded waters. The crystal was also favored by the observation that there was no increase in chain configurational entropy upon dissolution, because the free chain adopts only one conformation, as previously observed, but against intuitive expectations, apparently due to the persistence of the intramolecular O3-O5 hydrogen bond.

  • 3. Borriss, R.
    et al.
    Krah, M.
    Brumer, Harry
    KTH, Tidigare Institutioner                               , Bioteknologi.
    Kerzhner, M. A.
    Ivanen, D. R.
    Eneyskaya, E. V.
    Elyakova, L. A.
    Shishlyannikov, S. M.
    Shabalin, K. A.
    Neustroev, K. N.
    Enzymatic synthesis of 4-methylumbelliferyl (1 -> 3)-beta-D-glucooligosaccharides - new substrates for beta-1,3-1,4-D-glucanase2003Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 338, nr 14, s. 1455-1467Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The transglycosylation reactions catalyzed by beta-1,3-D-glucanases (laminaranases) were used to synthesize a number of 4-methylumbelliferyl (MeUmb) (1 --> 3)-beta-D-gluco-oligosaccharides having the common structure [beta-D-Glcp-(1 --> 3)](n)-beta-D-Glcp-MeUmb, where n = 1-5. The beta-1,3-D-glucanases used were purified from the culture liquid of Oerskovia sp. and from a homogenate of the marine mollusc Spisula sachalinensis. Laminaran and curdlan were used as (1 --> 3)-beta-D-glucan donor substrates, while MeUmb-beta-D-glucoside (MeUmbGlcp) was employed as a transglycosylation acceptor. Modification of [beta-D-Glcp-(1 --> 3)](2)-beta-D-Glcp-MeUmb (MeUmbG(3)) gives 4,6-O-benzylidene-D-glucopyranosyl or 4,6-O-ethylidene-D-glucopyranosyl groups at the non-reducing end of artificial oligosaccharides. The structures of all oligosaccharides obtained were solved by H-1 and C-13 NMR spectroscopy and electrospray tandem mass spectrometry. The synthetic oligosaccharides were shown to be substrates for a beta-1,3-1,4-D-glucanase from Rhodothermus marinus, which releases MeUmb from beta-di- and beta-triglucosides and from acetal-protected beta-triglucosides. When acting upon substrates with d.p. > 3, the enzyme exhibits an endolytic activity, primarily cleaving off MeUrnbGlcP and MeUmbG(2).

  • 4. Cuers, Julia
    et al.
    Unterieser, Inga
    Burchard, Walther
    Adden, Roland
    Rinken, Marian
    Mischnick, Petra
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Simultaneous determination of substituent patterns in partially acid hydrolyzed O-Me/O-Me-d(3)-cellulose and quantification of the obtained oligomers by HPLC-ESI-MS2012Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 348, s. 55-63Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Substituent patterns in oligosaccharide derivatives obtained from methyl cellulose were determined up to DP10 by electrospray ionization mass spectrometry employing separation of the oligomer fractions by HPLC. Oligosaccharides were labeled with meta-aminobenzoic acid after perdeuteromethylation and partial hydrolysis of methyl cellulose, enabling simultaneous quantification according to DP by HPLC/UV. Control of the HPLC-method was performed with a defined oligomer mixture obtained from beta-cyclodextrin. Results from LC-ESI-MS are discussed in comparison with those from syringe pump injection and compared to a calculated pattern for a random distribution. Programing of instrumental parameters optimized for each DP and avoidance of competition of successively eluting analytes in the electrospray process allowed extension of the established method for determination of the substitution pattern of cellulose derivatives along the polymer chain from DP5 to DP10 and thus a significant gain of information.

  • 5.
    Enebro, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Momcilovic, Dane
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Siika-Aho, Matti
    VTT Technical Research Centre of Finland, Espoo.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Liquid Chromatography combined with Mass Spectrometry for the Investigation of Endoglucanase Selectivity on Carboxymethyl Cellulose2009Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 344, nr 16, s. 2173-2181Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Endoglucanases are useful tools in the chemical structure analysis of cellulose derivatives. However, knowledge on the endoglucanase selectivity, which is of central importance for data interpretation, is still limited. In this study, new reverse-phase liquid chromatography mass spectrometry (LC-MS) methods were developed to investigate the selectivity of the endoglucanases Cel5A, cel7B, Cel45A, and Cel74A from the filamentous fungus Trichoderma reesei. The aim was to improve the identification of the regioisomers in the complex mixtures that are obtained after enzymatic hydrolysis. Reduction followed by per-O-methylation was performed in order to improve the separation in reverse-phase LC, increase MS sensitivity, and to facilitate structure analysis by MS/MS of O-carboxymethyl glucose and cellooligosaccharides. The cellulose selective enzymes that were investigated displayed interesting differences in enzyme selectivity on CMC substrates.

  • 6. Eneyskaya, E. V.
    et al.
    Brumer, Harry
    KTH, Tidigare Institutioner                               , Bioteknologi.
    Backinowsky, L. V.
    Ivanen, D. R.
    Kulminskaya, A. A.
    Shabalin, K. A.
    Neustroev, K. N.
    Enzymatic synthesis of beta-xylanase substrates: transglycosylation reactions of the beta-xylosidase from Aspergillus sp2003Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 338, nr 4, s. 313-325Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A beta-D-xylosidase with molecular mass of 250 +/- 5 kDa consisting of two identical subunits was purified to homogeneity from a cultural filtrate of Aspergillus sp. The enzyme manifested high transglycosylation activity in transxylosylation with p-nitrophenyl P-D-xylopyranoside (PNP-X) as substrate, resulting in regio- and stereoselective synthesis of p-nitrophenyl (PNP) beta-(1 --> 4)-D-xylooligosaccharides with dp 2-7. All transfer products were isolated from the reaction mixtures by HPLC and their structures established by electrospray mass spectrometry and H-1 and C-13 NMR spectroscopy. The glycosides synthesised, beta-Xyl-1 --> (4-beta-Xyl-1 -->)(n)4-beta-Xyl-OC6H4NO2-p (n = 1 - 5), were tested as chromogenic substrates for family 10 beta-xylanase from Aspergillus orizae (XynA) and family 11 beta-xylanase I from Trichoderma reesei (XynT) by reversed-phase HPLC and UV-spectroscopy techniques. The action pattern of XynA against the foregoing PNP beta-(1 --> 4)-D-xylooligosaccharides differed from that of XynT in that the latter released PNP mainly from short PNP xylosides (dp 2 - 3) while the former liberated PNP from the entire set of substrates synthesised.

  • 7.
    Gellerstedt, Göran
    et al.
    KTH, Tidigare Institutioner                               , Pappers- och massateknik.
    Li, Jiebing
    KTH, Tidigare Institutioner                               , Pappers- och massateknik.
    An HPLC method for the quantitative determination of hexeneuronic acid groups in chemical pulps1996Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 294, s. 41-51Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It has recently been demonstrated that 4-deoxy-L-threo-hex-4-enopyranosyluronic acid (''hexeneuronic acid'') is present in kraft pulps and linked to the xylan backbone. An analytical method for the quantitative determination of hexeneuronic acid groups has now been developed. The procedure involves a selective hydrolysis with mercuric acetate of the glucosidic linkage between the hexeneuronic acid group and the xylan chain, followed by oxidation with periodate to form P-formyl pyruvic acid. The latter is reacted with thiobarbituric acid, and the red-coloured adduct formed is separated by reverse phase HPLC and quantified by measuring the absorbance at 549 nm, Some kraft pulps have been analysed to illustrate the contribution of hexeneuronic acid groups to the total amount of oxidizable structures present in such pulps.

  • 8.
    Kong, Na
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Shimpi, Manishkumar R.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Park, Jae Hyeung
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Yan, Mingdi
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Carbohydrate conjugation through microwave-assisted functionalization of single-walled carbon nanotubes using perfluorophenyl azides2015Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 405, s. 33-38Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carbohydrate-functionalized single-walled carbon nanotubes (SWNTs) were synthesized using microwave-assisted reaction of perfluorophenyl azide with the nanotubes. The results showed that microwave radiation provides a rapid and effective means to covalently attach carbohydrates to SWNTs, producing carbohydrate-SWNT conjugates for biorecognition. The carbohydrate-functionalized SWNTs were furthermore shown to interact specifically with cognate carbohydrate-specific proteins (lectins), resulting in predicted recognition patterns. The carbohydrate-presenting SWNTs constitute a new platform for sensitive protein-or cell recognition, which pave the way for glycoconjugated carbon nanomaterials in biorecognition applications.

  • 9.
    Kong, Na
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Shimpi, Manishkumar R.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Park, Jaehyeung
    Univ Massachusetts, Dept Chem, Lowell, MA 01854 USA..
    Ramström, Olof
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    Yan, Mingdi
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Carbohydrate conjugation through microwave-assisted functionalization of single-walled carbon nanotubes using perfluorophenyl azides (vol 405, pg 33, 2015)2015Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 412, s. 80-80Artikkel i tidsskrift (Fagfellevurdert)
  • 10.
    Li, Jiebing
    et al.
    KTH, Tidigare Institutioner                               , Pappers- och massateknik.
    Gellerstedt, Göran
    KTH, Tidigare Institutioner                               , Pappers- och massateknik.
    The contribution to kappa number from hexeneuronic acid groups in pulp xylan1997Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 302, nr 3-4, s. 213-218Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The kappa number of chemical pulps is widely used both in mill operation and in laboratory work as a measure of the degree of delignification in pulping, oxygen delignification, and prebleaching. Recently, it has been shown that the kappa number reflects not only lignin but also carbohydrate structures sensitive to oxidation by permanganate, notably hexeneuronic acid groups linked to xylan. In the present work, the kappa number units originating from hexeneuronic acid groups calculated on a molar basis have been determined in two different ways, viz. by permanganate oxidation of model compounds and by selective elimination of hexeneuronic acid groups from a series of kraft pulps. The results are in good agreement with each other and demonstrate that 10 mu mol of hexeneuronic acid correspond to 0.84-0.86 kappa units. From kappa number determinations combined with hydrolysis of the pulp with mercuric acetate, it is possible to calculate the amount of hexeneuronic acid groups present in a pulp.

  • 11.
    Li, Jiebing
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Kisara, Koki
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Danielsson, Sverker
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Lindström, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Gellerstedt, Göran
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    An improved methodology for the quantification of uronic acid units in xylans and other polysaccharides2007Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 342, nr 11, s. 1442-1449Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Uronic acids can be quantified either by a colorimetric determination after treatment with concentrated sulfuric acid and carbazole or by gas chromatography after methanolysis and subsequent acetylation. Both methods suffer from incomplete hydrolysis, an unavoidable degradation of the products to be analysed, and an inability to separate and quantify different types of uronic acids. In the present work, the fundamental chemistry involved in the two methods has been evaluated, and some modifications to increase their accuracy are suggested. By combining the two methods, a complete quantification of all individual types of urome acids present in a sample can be achieved.

  • 12.
    Lindh, Erik L.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Bergenstråhle-Wohlert, Malin
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Terenzi, Camilla
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Salmén, Lennart
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Furó, Istvan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Non-exchanging hydroxyl groups on the surface of cellulose fibrils: The role of interaction with water2016Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 434, s. 136-142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interaction of water with cellulose stages many unresolved questions. Here 2H MAS NMR and IR spectra recorded under carefully selected conditions in 1H-2H exchanged, and re-exchanged, cellulose samples are presented. It is shown here, by a quantitative and robust approach, that only two of the three available hydroxyl groups on the surface of cellulose fibrils are exchanging their hydrogen with the surrounding water molecules. This finding is additionally verified and explained by MD simulations which demonstrate that the 1HO(2) and 1HO(6) hydroxyl groups of the constituting glucose units act as hydrogen-bond donors to water, while the 1HO(3) groups behave exclusively as hydrogen-bond acceptors from water and donate hydrogen to their intra-chain neighbors O(5). We conclude that such a behavior makes the latter hydroxyl group unreactive to hydrogen exchange with water.

  • 13.
    Malm, Erik
    et al.
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Bulone, Vincent
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Wickholm, Kristina
    Larsson, Per Tomas
    Iversen, Tommy
    The surface structure of well-ordered native cellulose fibrils in contact with water2010Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 345, nr 1, s. 97-100Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    CP/MAS C-13 NMR spectroscopy was used in combination with spectral fitting to examine the surface structure of hydrated cellulose I fibrils from Halocynthia and Gluconoacetobacter xylinus. To increase the spectral intensities and minimize signal overlap, G. xylinus celluloses site-specifically enriched in C-13 either on C4 or on both C1 and C6 were examined. The experimental data showed multiple C4 and C6 signals for the water accessible fibril surfaces in the highly crystalline celluloses. These signal multiplicities were attributed to structural features in the surface layers induced by the fibril interior, and could not be extracted by spectral fitting in celluloses with a lower degree of crystallinity such as cellulose from cotton.

  • 14.
    Norberg, Oscar
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Wu, Bin
    Thota, Niranjan
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Ge, Jian-Tao
    Fauquet, Germain
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Saur, Ann-Kathrin
    Aastrup, Teodor
    Dong, Hai
    Yan, Mingdi
    KTH, Skolan för kemivetenskap (CHE), Kemi. Department of Chemistry, University of Massachusetts Lowell, 1 University Ave., MA, 01854 Lowell, USA.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi. Department of Chemistry, University of Massachusetts Lowell, 1 University Ave., MA, 01854 Lowell, USA.
    Synthesis and binding affinity analysis of alpha 1-2-and alpha 1-6-O/S-linked dimannosides for the elucidation of sulfur in glycosidic bonds using quartz crystal microbalance sensors2017Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 452, s. 35-42Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The role of sulfur in glycosidic bonds has been evaluated using quartz crystal microbalance methodology. Synthetic routes towards alpha 1-2- and alpha 1-6-linked dimannosides with S-or O-glycosidic bonds have been developed, and the recognition properties assessed in competition binding assays with the cognate lectin concanavalin A. Mannose-presenting QCM sensors were produced using photoinitiated, nitrenemediated immobilization methods, and the subsequent binding study was performed in an automated flow-through instrumentation, and correlated with data from isothermal titration calorimetry. The recorded Kd-values corresponded well with reported binding affinities for the O-linked dimannosides with affinities for the alpha 1-2-linked dimannosides in the lower micromolar range. The S-linked analogs showed slightly disparate effects, where the alpha 1-6-linked analog showed weaker affinity than the O-linked dimannoside, as well as positive apparent cooperativity, whereas the alpha 1-2-analog displayed very similar binding compared to the O-linked structure. 

  • 15. Unterieser, Inga
    et al.
    Mischnick, Petra
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Labeling of oligosaccharides for quantitative mass spectrometry2011Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 346, nr 1, s. 68-75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Quantitative analysis of oligosaccharide mixtures and their derivatives by electrospray ionization mass spectrometry (ESI MS) is challenging, for example, due to different affinities of the analytes to alkali ions. To overcome this source of discrimination and to enhance signal intensity, labeling studies with cellobiose as model compound were performed with the goal to develop a rapid, easy, and robust method. Hydrazone formation with the permanently charged Girard's T reagent as well as reductive amination with five different charge providing amines were studied under various conditions. In both reaction types, the removal of water turned out to be the critical step because only under these conditions are the reactions pushed to completion. By working with only a slight excess of reagents, no purification is necessary to achieve excellent signal/noise ratios, avoiding further sources of discrimination. Comparing various reducing agents with respect to their selectivity and stability in the acidic reaction medium, 2-picoline borane turned out to be superior to the commonly used sodium cyanoborohydride. Thus, by replacement of the toxic NaCNBH3 by the more selective and stable, non-toxic 2-picoline borane, complete reductive amination with low amounts of reagents and without unlabeled alditol formation was achieved with o-aminobenzoic acid, a useful reagent for ESI MS in negative mode. For MS in positive mode Girard's T derivatization was very suitable.

  • 16.
    Zhang, Qiong
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Brumer, Harry
    KTH, Skolan för bioteknologi (BIO), Glykovetenskap.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Tu, Yaoquan
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    The adsorption of xyloglucan on cellulose: effects of explicit water and side chain variation2011Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 346, nr 16, s. 2595-2602Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interaction between para-crystalline cellulose and the cross-linking glycan xyloglucan (XG) plays a central role for the strength and extensibility of plant cell walls. The coating of XGs on cellulose surfaces is believed to be one of the most probable interaction patterns. In this work, the effects of explicit water and side chain variation on the adsorption of XGs on cellulose are investigated by means of atomistic molecular dynamics simulations. The adsorption properties are studied in detail for three XGs on cellulose I beta 1-10 surface in aqueous environment, namely GXXXGXXXG, GXXLGXXXG, and GXXFGXXXG, which differ in the length and composition of one side chain. Our work shows that when water molecules are included in the theoretical model, the total interaction energies between the adsorbed XGs and cellulose are considerably smaller than in vacuo. Furthermore, in water environment the van der Waals interactions prevail over the electrostatic interactions in the adsorption. Variation in one side chain does not have significant influence on the interaction energy and the binding affinity, but does affect the equilibrium structural properties of the adsorbed XGs to facilitate the interaction between both the backbone and the side chain residues with the cellulose surface. Together, this analysis provides new insights into the nature of the XG-cellulose interaction, which helps to further refine current molecular models of the composite plant cell wall.

  • 17.
    Zhang, Yujia
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi.
    Li, Jiebing
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Lindström, Mikael E.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Mischnick, Petra
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. Technische Universität Braunschweig, Germany .
    Relative reactivities in the O-methylation of glucomannans: the influence of stereochemistry at C-2 and the solvent effect2015Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 402, s. 172-179Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main hemicellulose in softwood, glucomannan (GM), structurally resembles cellulose but has quite different physical and chemical properties. In addition to branching and original acetylation, the only other difference between these two beta-1,4-linked glycans is the configuration at C-2 in approximately 80% of the sugar residues. In contrast to glucose, the 2-OH in mannose has an axial orientation. The influence of this stereochemistry on the relative reactivities of glucosyl compared to mannosyl units in methylation reactions are studied in this work. Glucomannan isolated from spruce (SGM) and commercially available konjac glucomannan (KGM) was methylated in DMSO/Li-dimsyl/MeI and water/NaOH/MeI system, respectively. In the early stage of the reaction, the glucose part of the SGM achieved slightly higher DS values than the mannose residues, but the overall relative rate constants were close to 1:1. The order of reactivities in glucose was k(2) > k(3) > k(6) and k(3) > k(2) > k(6) for mannose (in DMSO/Li-dimsyl/MeI). The rate constants did not remain constant, but k(3) decreased when k(2) increased for both epimeric sugars. In water/NaOH/MeI, the methylation of the primary 6-OH was much more pronounced with an order of reactivity of O-6 > O-2 > O-3 for mannose and O-2 > O-6 > O-3 for glucose. The results are discussed with respect to the OH-acidity and the stereoelectronic, sterical, and solvent effects.

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