Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Self-organization of polyurethane pre-polymers as studied by self-consistent field theory
Li, Feng ; Tuinier, Remco ; Casteren, Ilse Van; Tennebroek, Ronald ; Overbeek, Ad ; Leermakers, F.A.M. - \ 2016
Macromolecular Theory and Simulations 25 (2016)1. - ISSN 1022-1344 - p. 16 - 27.

Using self-consistent field (SCF) theory, we studied the self-assembly characteristics of polyurethane pre-polymer dispersions in aqueous solutions. With a molecularly detailed model implementing the Scheutjens-Fleer discretization scheme, it is shown how the stability, equilibrium size, and internal structure of the (swollen) micelles in polyurethane (PU) dispersions depend on the chemical structure and the molecular composition of the charged pre-polymer mixtures. The stability region of these micelles is found to increase when acid groups become deprotonated and when the ionic strength is lowered. Insight into the physical-chemical behavior of PU pre-polymer dispersions is important for the subsequent process of film formation from the PU dispersions for the final coating properties. Using self-consistent field (SCF) theory with a molecularly detailed model, the authors study the self-assembly of polyurethane pre-polymer dispersions in aqueous solutions. Insight into the physical-chemical behavior of PU pre-polymer dispersions is obtained. Details like radial volume fraction distribution of six representative PU pre-polymers and water on a single swollen micelle are shown in this paper.

Disclosing the carbohydrate modifying network of Aspergillus niger by functional genomics
Zandleven, J.S. ; Oostveen-van Casteren, W.H.M. van; Vincken, J.P. ; Beldman, G. ; Voragen, A.G.J. - \ 2002
In: Summer course Glycosciences Wageningen : VLAG Graduate School - p. 53 - 53.
The use of enzymes in expopolysaccharide research
Casteren, W.H.M. van; Schols, H.A. ; Beldman, G. ; Voragen, A.G.J. - \ 2001
In: First International Symposium on Exopolysaccharides from Lactic Acid Bacteria, Brussel 16-19 May 2001 / L. de Vuyst, B. Degeest. - Brussel : IMDO, VUB, 2001 - p. 26 - 26.
Effects of structural modifications on some physical characteristics of exopolysaccharides from Lactococcus lactis
Tuinier, R. ; Casteren, W.H.M. van; Looijesteijn, P.J. ; Schols, H.A. ; Voragen, A.G.J. ; Zoon, P. - \ 2001
Biopolymers 59 (2001). - ISSN 0006-3525 - p. 160 - 166.
The relationship between the primary structure and the chain stiffness of exopolysaccharides (EPSs) and modified EPSs produced by two strains of Lactococcus lactis subsp. cremoris was investigated. The molar mass and radius of gyration of these exopolysaccharides were analyzed by multiangle static light scattering after size-exclusion chromatography. From these results and the chemical structure of the repeating units of the investigated EPSs, the Kuhn lengths could be calculated. We found that the initial Kuhn lengths of the two native EPSs are similar. Modification of the EPSs by removing parts of the side groups resulted in a decrease in both the absolute value and the normalized value of the Kuhn length. It is therefore concluded that partial removal of the side groups of these polysaccharides could make them less efficient as thickeners if no specific interaction with other components occurs
Structural characterisation and enzymic modification of the exopolysaccharide produced by Lactococcus lactis subsp. cremoris B891
Casteren, W.H.M. van; Waard, P. de; Dijkema, C. ; Schols, H.A. ; Voragen, A.G.J. - \ 2000
Carbohydrate Research : an international journal 327 (2000). - ISSN 0008-6215 - p. 411 - 422.
Lactococcus lactis subsp. cremoris B891 grown on whey permeate produced an exopolysaccharide containing -Gal and -Glc in a molar ratio of 2:3. The polysaccharide was partially O-acetylated. By means of HF solvolysis, O-deacetylation, enzymic modification, sugar linkage analysis and 1D/2D NMR studies the exopolysaccharide was shown to be composed of repeating units with the following structure:
Purification and characterisation of a ß-galactosidase from Aspergillus aculeatus with activity towards (modified) exopolysaccharides from Lactococcus lactis subsp. Cremoris B39 and B891
Casteren, W.H.M. van; Eimermann, M. ; Broek, L.A.M. van den; Vincken, J.P. ; Schols, H.A. ; Voragen, A.G.J. - \ 2000
Carbohydrate Research : an international journal 329 (2000). - ISSN 0008-6215 - p. 75 - 85.
Structural characterisation and enzymic modification of the exopolysaccharide produced by Lactococcus lactis subsp. cremoris B39
Casteren, W.H.M. van; Dijkema, C. ; Schols, H.A. ; Beldman, G. ; Voragen, A.G.J. - \ 2000
Carbohydrate Research : an international journal 324 (2000). - ISSN 0008-6215 - p. 170 - 181.
Structural characterisation and enzymic modification of exopolysaccharides from Lactococcus lactis
Casteren, W. van - \ 2000
Agricultural University. Promotor(en): A.G.J. Voragen; Henk Schols. - S.l. : S.n. - ISBN 9789058082206 - 114
lactococcus lactis - polysacchariden - polysaccharides
<p>Since ancient times, lactic acid bacteria have been used for the preservation of food. Some of these bacteria are able to produce exopolysaccharides (EPSs), which may contribute to the peculiar rheology and texture of, for example, milk-derived products. Insight into the relationship between the chemical structure of EPSs and their physical properties can lead to tailor-made polysaccharides, which meet particular requirements in terms of structure and function. In this thesis, the elucidation of the chemical structures of three exopolysaccharides from <em>Lactococcus lactis</em> subsp. <em>cremoris</em> is described. Enzymes are used as a tool during the structural characterisation and modification of EPS and the action of three enzymes having activity towards (chemically modified) EPSs is investigated as well. Finally, a start has been made within this project to study the effect of structural changes of EPSs on the physical properties.</p><p>In chapter 1, a brief general introduction into the research subject is given. Besides background information about the use of bacterial EPSs in food and the biosynthesis of EPS, attention is paid to common features in EPS structures from lactic acid bacteria. Different ways to obtain structurally related EPSs are presented and the use of enzymes in polysaccharide research is outlined.</p><p>Chapter 2 describes the study of the chemical structure of EPS B40, explaining earlier reported analytical discrepancies.The EPS contains rhamnose:galactose:glucose:phosphate in a molar ratio of 1:1.3:2:1.1. <sup>31</SUP>P NMR indicated that a single phosphate group is present as a phosphodiester. EPS B40 has chemically been modified using 0.3 M H <sub>2</sub> SO <sub>4</sub> , 28 M HF or 2 M NaOH. From these modifications it is concluded that during the hydrolysis step prior to sugar composition analysis the galactose 3-phosphate linkages are split only partially and that, consequently, the amount of galactose is underestimated. The backbone of HF-modified EPS B40 can be degraded by a crude cellulase preparation from <em>Trichoderma viride</em> . Purification and characterisation of the obtained oligomers (chapter 3), together with the characterisation of the polymer (chapter 2), has resulted in a chemical structure for EPS B40 identical to the repeating unit already described for EPS SBT 0495:</p><DIV ALIGN="Center"><img src="/wda/abstracts/i2790_01.gif" WIDTH="426" HEIGHT="100" ALT="Inline Image Figure 01" BORDER="0"/></DIV><p>In chapter 3, the enzyme activity responsible for the degradation of HF-modified EPS B40 is identified as an endoglucanase (endoV). Thus, after complete removal of galactosyl residues and phosphate and partial removal of rhamnosyl residues, endo <em>glucanase</em> is able to cleave the backbone consisting of glucosyl and <em>galactosyl</em> residues. Characterisation of the resulting homologous series of oligomers by MS and NMR unequivocally demonstrated that endoV is able to cleave theβ-(1→4) linkage between two glucopyranosyl residues when the galactopyranosyl residue towards the nonreducing end is unsubstituted. The mode of action of endoV on HF-modified EPS B40 is discussed on the basis of the subsite model for endoV, described in literature. The crude cellulase preparation from <em>T. viride</em> has also been shown to contain a phosphatase able to act on EPS B40 after removal of rhamnosyl and galactosyl residues by mild CF <sub>3</sub> CO <sub>2</sub> H treatment.</p><p>In chapter 4, the structural elucidation of EPS B39 is outlined. This novel exopolysaccharide structure contains l-Rha, d-Gal and d-Glc in a molar ratio of 2:3:2. Enzymic modification, methylation analysis and 1D/2D NMR experiments (both <sup>1</SUP>H- <sup>1</SUP>H and <sup>1</SUP>H- <sup>13</SUP>C) revealed that EPS B39 consists of a branched heptasaccharide repeating unit with the following structure:</p><DIV ALIGN="Center"><img src="/wda/abstracts/i2790_02.gif" WIDTH="554" HEIGHT="94" ALT="Inline Image Figure 02" BORDER="0"/></DIV><p>Chapter 5 describes the chemical structure of EPS B891, which contains d-Gal and d-Glc in a molar ratio of 2:3. The polysaccharide is partially <em>O</em> -acetylated. By means of HF solvolysis, <em>O</em> -deacetylation, enzymic modification, methylation analysis and 1D/2D NMR studies the novel exopolysaccharide is shown to be composed of repeating units with the following structure:</p><DIV ALIGN="Center"><img src="/wda/abstracts/i2790_03.gif" WIDTH="470" HEIGHT="154" ALT="Inline Image Figure 03" BORDER="0"/></DIV><p>EPS B39 and <em>O</em> -deacetylated EPS B891 both contain lactosyl side chains and it is demonstrated that the terminally linked galactosyl residues can be removed by using a crude commercial enzyme preparation from <em>Aspergillus aculeatus</em> . The purification and characterisation of theβ-galactosidase responsible for this modification is described in chapter 6. The enzyme has a molecular mass of approximately 120 kDa, a pI between 5.3-5.7 and is optimally active at pH 5.4 and 55-60 <sup>o</SUP>C. Based on the N-terminal amino acid sequence, the enzyme probably belongs to family 35 of the glycosyl hydrolases. The catalytic mechanism is shown to be retaining and transglycosylation products are demonstrated using lactose as a substrate. Theβ-galactosidase is able to release terminally linked galactosyl residues from EPS B891 in presence of acetyl groups, but the hydrolysing rate after <em>O</em> -deacetylation is higher. Furthermore, <em>O</em> -deacetylated EPS B891 is degalactosylated faster than EPS B39.</p><p>In chapter 7, the results of this thesis are discussed. Emphasis is placed on the approach of using enzymes in structure (-function) studies of exopolysaccharides. Furthermore, the use of (modified) exopolysaccharides for characterising enzyme activities is outlined. Finally, the influence of various structural modifications on the physical properties of EPSs is briefly discussed.</p>
Influence of different substrate limitations on the yield, composition and molecular mass of exopolysaccharides produced by Lactococcus lactis subsp. cremoris in continuous cultures
Looijesteijn, P.J. ; Casteren, W.H.M. van; Tuinier, R. ; Doeswijk-Voragen, C.H.L. ; Hugenholtz, J. - \ 2000
Journal of Applied Microbiology 89 (2000). - ISSN 1364-5072 - p. 116 - 122.
Endoglucanase V from Trichoderma viride is able to act on modified exopolysaccharide from Lactococcus lactis subsp. cremoris B40
Casteren, W.H.M. van; Kabel, M.A. ; Dijkema, C. ; Schols, H.A. ; Beldman, G. ; Voragen, A.G.J. - \ 1999
In: 3rd Carbohydrate Bioengineering Meeting, Newcastele upon Tyne, 11-14 April 1999. - University of Newcastle upon Tyne, 1999 - p. 3.7 - 3.7.
Endoglucanase V and a phosphatase from Trichoderma viride are able to act on modified exopolysaccharide from Lactococcus lactis subsp. cremoris B40
Casteren, W.H.M. van; Kabel, M.A. ; Dijkema, C. ; Schols, H.A. ; Beldman, G. ; Voragen, A.G.J. - \ 1999
Carbohydrate Research : an international journal 317 (1999). - ISSN 0008-6215 - p. 131 - 144.
Enzymatic modification of exopolysaccharides from lactic acid bacteria
Casteren, W.H.M. van; Dijkema, C. ; Schols, H.A. ; Beldman, G. ; Voragen, A.G.J. - \ 1999
In: 3rd Carbohydrate Bioengineering Meeting, Newcastele upon Tyne, 11-14 April 1999. - University of Newcastle upon Tyne, 1999 - p. 6.15 - 6.15.
Endoglucanase V from Trichoderma viride is able to act on modified exopolysaccharide from Lactococcus lactis subsp. Cremoris B40.
Casteren, W.H.M. van; Kabel, M.A. ; Dijkema, C. ; Schols, H.A. ; Beldman, G. ; Voragen, A.G.J. - \ 1998
In: Proceedings of the 8th International Cell Wall Meeting, Norwich, UK (1998) 2.24
Structural variation and levels of water-extractable arabinogalactan-peptide in European wheat flours.
Loosveld, A. ; Maes, C. ; Casteren, W.H.M. van; Schols, H.A. ; Grobet, P.J. ; Delcour, J.A. - \ 1998
Cereal Chemistry 75 (1998). - ISSN 0009-0352 - p. 815 - 819.
Recent Progress in high-performance anion-exchange chromatography/ionspray mass spectrometry for molecular mass determination and characterization of carbohydrates using static and scanning array detection.
Hoeven, R.A.M. van der; Tjaden, U.R. ; Greef, J. van der; Casteren, W.H.M. van; Schols, H.A. ; Voragen, A.G.J. ; Bruggink, C. - \ 1998
Journal of Mass Spectrometry 33 (1998). - ISSN 1076-5174 - p. 377 - 386.
Characterisation and modification of the exopolysaccharide produced by Lactococcus lactis subsp. cremoris B40.
Casteren, W.H.M. van; Dijkema, C. ; Schols, H.A. ; Beldman, G. ; Voragen, A.G.J. - \ 1998
Carbohydrate Polymers 37 (1998). - ISSN 0144-8617 - p. 123 - 130.
The chemical structure of an exopolysaccharide produced by Lactococcus lactis subsp. cremoris B40 is studied, explaining earlier reported analytical discrepancies. The EPS was found to have a molecular mass of 6.8x105gmol-1 and a molar ratio of rhamnose:galactose:glucose:phosphorus of 1:1.3:2:1.1. 31P NMR indicated that a single phosphate group is present as a phosphodiester. EPS B40 was chemically modified using 0.6M H2SO4, 28M HF or 2M NaOH. From these modifications it could be concluded that galactose 1-phosphate was linked at the 3-position of 1,2,3,4-linked galactose in the backbone of the EPS. Furthermore, it appeared that during the hydrolysis step of the sugar composition analysis the galactose 3-phosphate linkages were only partially split and that, as a result, the amount of galactose was underestimated in presence of phosphate. Finally, it was demonstrated that a crude cellulase preparation was able to degrade dephosphorylated and partially de-rhamnosylated EPS.
Analysis of the exopolysaccharides produced by Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772 grown in continuous culture on glucose and fructose.
Grobben, G.J. ; Casteren, W.H.M. van; Schols, H.A. ; Oosterveld, A. ; Sala, G. ; Smith, M.R. ; Sikkema, J. ; Bont, J.A.M. de - \ 1997
Applied Microbiology and Biotechnology 48 (1997)4. - ISSN 0175-7598 - p. 516 - 521.
The exopolysaccharides produced by Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772 grown in defined medium were investigated. At equal cell densities, the strain produced 95 mg l−1 exopolysaccharides with glucose and 30 mg l−1 with fructose as the carbohydrate source. High-performance size-exclusion chromatography of the exopolysaccharides produced on glucose showed the presence of two fractions with relative molecular masses (M r) of 1.7 × 106 and 4 × 104 in almost equal amounts. The exopolysaccharides produced on fructose contained mainly a fraction of low M r of 4 × 104. The high-M r fraction of the purified exopolysaccharides produced on glucose appeared to have a sugar composition of galactose, glucose and rhamnose in the molar ratio of 5:1:1, whereas the low-M r weight fraction contained galactose, glucose and rhamnose in the molar ratio of approximately 11:1:0.4. The purified exopolysaccharide fractions produced on fructose showed comparable ratios. The high-molecular-mass fractions contained terminally linked galactose, 1,2,3-linked galactose, 1,3,4-linked galactose, 1,3-linked glucose and terminally linked rhamnose. The low-molecular-mass fractions contained mainly 1,3-linked galactose and 1,6-linked galactose and lower amounts of other sugar linkages. The production of the high-M r fractions appeared to be dependent on the carbohydrate source, whereas the low-M r fractions were produced more continuously.
Recent progress in high-performance anion-exchange chromatography/ionspray mass spectrometry for molecular mass determination and characterization of carbohydrates using static and scannin array detection.
Hoeven, R.A.M. van der; Tjaden, U.R. ; Greef, J. van der; Casteren, W.H.M. van; Schols, H.A. ; Voragen, A.G.J. ; Brugging, C. - \ 1997
In: International Symposium 'Non-digestible oligosaccharides: healthy food for the colon?', Wageningen, NL - p. 140 - 140.
Modifications of extracellular polysaccharides from Lactococcus lactis subsp. cremoris.
Casteren, W.H.M. van; Schols, H.A. ; Beldman, G. ; Voragen, A.G.J. - \ 1997
In: 2nd Carbohydrate Bioengineering Meeting, Rochelle, France - p. 59 - 59.
Purification and characterisation of extracellular polysaccharide from Lactobacillus lactis B40.
Casteren, W.H.M. van; Schols, H.A. ; Beldman, G. ; Voragen, A.G.J. - \ 1996
In: VLAG Congr. Als speler op agro-food kennismarkt, Wageningen (1996) Ch.18
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