51
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Harnau L, Winkler RG, Reineker P. Influence of Polydispersity on the Dynamic Structure Factor of Macromolecules in Dilute Solution. Macromolecules 1999. [DOI: 10.1021/ma990450f] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ludger Harnau
- Abteilung Theoretische Physik, Universität Ulm, 89069 Ulm, Germany
| | | | - Peter Reineker
- Abteilung Theoretische Physik, Universität Ulm, 89069 Ulm, Germany
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52
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Ridout MJ, Brownsey GJ, Gunning AP, Morris VJ. Characterisation of the polysaccharide produced by Acetobacter xylinum strain CR1/4 by light scattering and atomic force microscopy. Int J Biol Macromol 1998; 23:287-93. [PMID: 9849626 DOI: 10.1016/s0141-8130(98)00057-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The molecular weight of the extracellular polysaccharide (CR1/4) produced by Acetobacter xylinum strain CR1/4 has been shown to be dependent upon growth conditions. Under normal growth conditions a high molecular weight polysaccharide ( > 1 x 10(6) Da) is produced. Maintaining the pH at 5 results in an order of magnitude increase in the total yield of polysaccharide, but also an order of magnitude decrease in molecular weight. Analysis of the CR1/4 polysaccharides by the techniques of atomic force microscopy and static light scattering suggests that they are double helices. In solution the molecules behave as stiff coils with a Kuhn statistical segment length of 325 nm.
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Affiliation(s)
- M J Ridout
- Food Biophysics Department, Institute of Food Research, Norwich Laboratory, Colney, UK
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53
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Harding SE. The intrinsic viscosity of biological macromolecules. Progress in measurement, interpretation and application to structure in dilute solution. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1998; 68:207-62. [PMID: 9652172 DOI: 10.1016/s0079-6107(97)00027-8] [Citation(s) in RCA: 233] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- S E Harding
- National Centre for Macromolecular Hydrodynamics, University of Nottingham, School of Biological Sciences, Sutton Bonington, U.K
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54
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Harnau L, Winkler RG, Reineker P. Remarks on the Interpretation of Dynamic Light Scattering from Gellan in Dilute Solution. Macromolecules 1997. [DOI: 10.1021/ma970833i] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ludger Harnau
- Abteilung Theoretische Physik, Universität Ulm, 89069 Ulm, Germany
| | | | - Peter Reineker
- Abteilung Theoretische Physik, Universität Ulm, 89069 Ulm, Germany
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55
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56
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Petekidis G, Vlassopoulos D, Galda P, Rehahn M, Ballauff M. Determination of Chain Conformation of Stiff Polymers by Depolarized Rayleigh Scattering in Solution. Macromolecules 1996. [DOI: 10.1021/ma961128x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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57
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Berth G, Dautzenberg H, Christensen BE, Harding SE, Rother G, Smidsrød O. Static Light Scattering Studies on Xanthan in Aqueous Solutions. Macromolecules 1996. [DOI: 10.1021/ma9515386] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gisela Berth
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology, University of Trondheim, NTH, N-7034 Trondheim, Norway, Max Planck Institute for Colloid and Interface Science, D-14513 Teltow, Germany, and Department of Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington LE12 5RD, U.K
| | - Herbert Dautzenberg
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology, University of Trondheim, NTH, N-7034 Trondheim, Norway, Max Planck Institute for Colloid and Interface Science, D-14513 Teltow, Germany, and Department of Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington LE12 5RD, U.K
| | - Bjørn E. Christensen
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology, University of Trondheim, NTH, N-7034 Trondheim, Norway, Max Planck Institute for Colloid and Interface Science, D-14513 Teltow, Germany, and Department of Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington LE12 5RD, U.K
| | - Stephen E. Harding
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology, University of Trondheim, NTH, N-7034 Trondheim, Norway, Max Planck Institute for Colloid and Interface Science, D-14513 Teltow, Germany, and Department of Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington LE12 5RD, U.K
| | - Gudrun Rother
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology, University of Trondheim, NTH, N-7034 Trondheim, Norway, Max Planck Institute for Colloid and Interface Science, D-14513 Teltow, Germany, and Department of Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington LE12 5RD, U.K
| | - Olav Smidsrød
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology, University of Trondheim, NTH, N-7034 Trondheim, Norway, Max Planck Institute for Colloid and Interface Science, D-14513 Teltow, Germany, and Department of Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington LE12 5RD, U.K
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58
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Christensen BE, Smidsrød O, Stokke BT. Metastable, Partially Depolymerized Xanthans and Rearrangements toward Perfectly Matched Duplex Structures. Macromolecules 1996. [DOI: 10.1021/ma951445o] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bjørn E. Christensen
- Norwegian Biopolymer Laboratory, Departments of Biotechnology and of Physics and Mathematics, Norwegian University of Science and Technology, N-7034 Trondheim, Norway
| | - Olav Smidsrød
- Norwegian Biopolymer Laboratory, Departments of Biotechnology and of Physics and Mathematics, Norwegian University of Science and Technology, N-7034 Trondheim, Norway
| | - Bjørn T. Stokke
- Norwegian Biopolymer Laboratory, Departments of Biotechnology and of Physics and Mathematics, Norwegian University of Science and Technology, N-7034 Trondheim, Norway
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59
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Patrick Gunning A, Kirby AR, Morris VJ. Imaging xanthan gum in air by ac “tapping” mode atomic force microscopy. Ultramicroscopy 1996. [DOI: 10.1016/0304-3991(96)00032-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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60
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Milas M, Reed WF, Printz S. Conformations and flexibility of native and re-natured xanthan in aqueous solutions. Int J Biol Macromol 1996; 18:211-21. [PMID: 8729033 DOI: 10.1016/0141-8130(95)01080-7] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The conformation and flexibility of sonicated 'native' and 're-natured' xanthan have been investigated by size exclusion chromatography (SEC) with coupled multi-angle light scattering and viscosity detectors. 'Native' xanthan (NX) refers to xanthan dissolved in moderate ionic strength aqueous solution, which has not been exposed either to high temperature or very low ionic strength, and 're-natured' xanthan (RX) here refers to xanthan which has been heated above the conformational melting temperature and then recooled. The mass distributions of the NX and RX are virtually identical, implying that the RX does not involve aggregates of, or disassociated fragments of, NX. The flexibilities and conformations between NX and RX, however, are strikingly different; RX is far stiffer than NX, the persistence lengths being roughly 1000 A and 300 A, respectively, and the mass per unit length M/L of the RX is roughly double that of NX. With estimated M/L of 200 Da/A and 98 Da/A, respectively, the results strengthen the notion that RX is double stranded, whereas as NX appears single stranded. The nature and mechanism of formation of the double-stranded form is still unclear, and a few speculative scenarios are suggested. Finally, preliminary results on the kinetics of xanthan self-association in HCI are presented which illustrate the complexity of such processes in xanthan.
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Affiliation(s)
- M Milas
- Centre de Recherches sur les Macromolecules Végétales (CERMAV), Grenoble, France
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61
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Abstract
Techniques have been developed for the routine reliable imaging of polysaccharides by atomic force microscopy (AFM). The polysaccharides are deposited from aqueous solution onto the surface of freshly cleaved mica, air dried, and then imaged under alcohols. The rationale behind the development of the methodology is described and data is presented for the bacterial polysaccharides xanthan, acetan, and the plant polysaccharides l-carrageenan and pectin. Studies on uncoated polysaccharides have demonstrated the improved resolution achievable when compared to more traditional metal-coated samples or replicas. For acetan the present methodology has permitted imaging of the helical structure. Finally, in addition to data obtained on individual polysaccharides, AFM images have also been obtained of the network structures formed by kappa-carrageenan and gellan gum.
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Affiliation(s)
- A R Kirby
- Institute of Food Research, Norwich Laboratory, UK
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62
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63
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Gunning AP, Kirby AR, Morris VJ, Wells B, Brooker BE. Imaging bacterial polysaccharides by AFM. Polym Bull (Berl) 1995. [DOI: 10.1007/bf00423359] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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64
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Physico-chemical studies on a commercial food-grade xanthan — I. Characterisation by sedimentation velocity, sedimentation equilibrium and viscometry. Carbohydr Polym 1995. [DOI: 10.1016/0144-8617(95)00044-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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65
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Grimm A, Krüger E, Burchard W. Solution properties of β-D-(1, 3)(1, 4)-glucan isolated from beer. Carbohydr Polym 1995. [DOI: 10.1016/0144-8617(95)00056-d] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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66
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Ridout MJ, Brownsey GJ, Morris VJ, Cairns P. Physicochemical characterization of an acetan variant secreted by Acetobacter xylinum strain CR1/4. Int J Biol Macromol 1994; 16:324-30. [PMID: 7727347 DOI: 10.1016/0141-8130(94)90064-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Chemical mutagenesis has been used to produce mutants of Acetobacter xylinum NRRL B42 that are cellulose-negative and that produce variants of the acetan structure deficient in the side-chain sugar residues. The product of A. xylinum strain CR1/4 has been shown to possess a tetrasaccharide repeat unit with the side chain terminating in glucuronic acid. X-ray diffraction studies of oriented fibres suggest that the polysaccharide CR1/4 forms a fivefold helix with a pitch of 4.8 nm. Light-scattering studies on CR1/4 solutions suggest a molecular weight of 1.2 x 10(6) with radii of gyration values of 86 nm (aqueous solution) and 67 nm (0.1 M NaCl solution). The magnitude of the measured radii of gyration and the shape of the Holtzer plots suggest that CR1/4 can be described as a stiff coil. Preliminary differential scanning calorimetry data show melting behaviour consistent with order-disorder transitions of a charged helical structure. Rheological studies have revealed new synergistic interactions of CR1/4 with locust bean gum. Comparative studies of acetan and CR1/4 show that decreasing the length of the side chain enhances the solution viscosity.
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Affiliation(s)
- M J Ridout
- Institute of Food Research, Norwich laboratory, Colney, UK
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67
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Gamini A, Mandel M. Physicochemical properties of aqueous xanthan solutions: static light scattering. Biopolymers 1994; 34:783-97. [PMID: 8025222 DOI: 10.1002/bip.360340610] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The secondary structure of xanthan in solutions of relatively low salt concentration and at room temperature has been investigated using static light scattering experiments. Additional evidence has been found for a dimeric structure at 25 degrees C in 0.01 M NaCl. From the experimental z-average mean square (ms) radius of gyration, a value for the persistence length p has been estimated, taking explicitly into account the polydispersity of the three samples used, which has been established by gel permeation chromatography (GPC) measurements. The experimental particle scattering functions of the three samples are consistent with theoretical estimates for polydisperse systems with the same value of p = 65 +/- 10 nm and the molar mass per unit length for a dimeric structure. This secondary structure remains unaffected by the ionic strength in the 0.005-0.01 M range. Partial aggregation seems to occur at higher NaCl concentrations. Light scattering and GPC data show that heating the xanthan 0.01 M NaCl solutions to about 70 degrees C considerably reduces the Mw of the low molar mass sample (2.3 x 10(5) g.mol-1), contrary to what is observed for the high molar mass sample (1.8 x 10(6) g.mol-1). These experimental findings can be accounted for by a partial temperature-induced dissociation of the xanthan dimers according to an all-or-none mechanism.
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Affiliation(s)
- A Gamini
- Department of Physical and Macromolecular Chemistry, Gorlaeus Laboratories, Leiden University, The Netherlands
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68
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Stokke BT, Elgsaeter A. Conformation, order-disorder conformational transitions and gelation of non-crystalline polysaccharides studied using electron microscopy. Micron 1994; 25:469-91. [PMID: 7850352 DOI: 10.1016/0968-4328(94)00040-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Direct imaging of polysaccharides using transmission electron microscopy (EM) is an important alternative to physical characterization of non-crystalline polysaccharides in solution. The polymer nature of stiff-chain polysaccharides is quite apparent from direct visualization of the electron micrographs, despite the fact that commonly employed preparation techniques reduce the resolution limit to about 1-2 nm. Electron microscopy has recently been used to study polysaccharides with emphasis both on quantitative properties like contour length, end-to-end distance and chain stiffness, and on qualitative structural features such as cyclization at the macromolecular level. The structural richness observed for polysaccharides of the beta-D0glucan family after a denaturation-renaturation treatment of the specimen, in particular, illustrates the unique potential of EM as a tool for obtaining conformational information about carbohydrate macromolecules. Examples of the latter also include the recent discoveries of cyclic beta-D-glucan and l-carrageenan structures. The EM technique provides information that is not only complementary to what can be obtained using other physical techniques, but also offers important insight otherwise masked by the averaging implicit in most physical techniques used to study aqueous polysaccharide solutions.
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Affiliation(s)
- B T Stokke
- Department of Physics, Norwegian Institute of Technology, University of Trondheim
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69
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Conformation dependent depolymerisation kinetics of polysaccharides studied by viscosity measurements. Carbohydr Polym 1994. [DOI: 10.1016/0144-8617(94)90070-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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70
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71
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72
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Lang P, Kajiwara K. Investigations of the architecture of tamarind seed polysaccharide in aqueous solution by different scattering techniques. JOURNAL OF BIOMATERIALS SCIENCE. POLYMER EDITION 1993; 4:517-28. [PMID: 8241067 DOI: 10.1163/156856293x00177] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The architecture of tamarind seed polysaccharide (TSP) has been investigated by light scattering (LS), small angle X-ray scattering (SAXS) and synchrotron radiation scattering (SRSAXS). The experimental data show that TSP in aqueous solution consists of multi stranded aggregates, with a high degree of particle stiffness. The angular dependence of the scattered intensity is typical for wormlike chains. Data evaluation on the basis of this model yields a statistical Kuhn segment length lK = 150 nm. The cross sectional radius of gyration is estimated as Rgcs = 6.0 +/- 0.5 A, which is more than twice the value, published for single stranded polysaccharides. Correspondingly, the experimental value of the linear mass density, measured by LS, is about five times higher than the theoretical value calculated from the primary structure.
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Affiliation(s)
- P Lang
- Kyoto Institute of Technology, Japan
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73
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Gidley MJ, Lillford PJ, Rowlands DW, Lang P, Dentini M, Crescenzi V, Edwards M, Fanutti C, Reid JS. Structure and solution properties of tamarind-seed polysaccharide. Carbohydr Res 1991; 214:299-314. [PMID: 1769022 DOI: 10.1016/0008-6215(91)80037-n] [Citation(s) in RCA: 134] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The major polysaccharide in tamarind seed is a galactoxyloglucan for which the ratios galactose:xylose:glucose are 1:2:25:2.8. A minor polysaccharide (2-3%) contains branched (1----5)-alpha-L-arabinofuranan and unbranched (1----4)-beta-D-galactopyranan features. Small-angle X-ray scattering experiments gave values for the cross-sectional radius of the polymer in aqueous solution that were typical of single-stranded molecules. Marked stiffness of the chain (C infinity 110) was deduced from static light-scattering studies and is ascribed partially to the restriction of the motion of the (1----4)-beta-D-glucan backbone by its extensive (approximately 80%) glycosylation. The rigidity of the polymer caused significant draining effects which heavily influenced the hydrodynamic behaviour. The dependence of "zero-shear" viscosity on concentration was used to characterise "dilute" and "semi-dilute" concentration regimes. The marked dependence on concentration in the "semi-dilute" region was similar to that for other stiff neutral polysaccharide systems, ascribed to "hyper-entanglements", and it is suggested that these may have arisen through a tenuous alignment of stiffened chains.
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Affiliation(s)
- M J Gidley
- Unilever Research Laboratory, Great Britain
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74
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Rau DC, Parsegian VA. Direct measurement of forces between linear polysaccharides xanthan and schizophyllan. Science 1990; 249:1278-81. [PMID: 2144663 DOI: 10.1126/science.2144663] [Citation(s) in RCA: 113] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Direct osmotic stress measurements have been made of forces between helices of xanthan, an industrially important charged polysaccharide. Exponentially decaying hydration forces, much like those already measured between lipid bilayer membranes or DNA double helices, dominate the interactions at close separation. Interactions between uncharged schizophyllans also show the same kind of hydration force seen between xanthans. In addition to the practical possibilities for modifying solution and suspension properties through recognition and control of molecular forces, there is now finally the opportunity for theorists to relate macroscopic properties of a polymer solution to the microscopic properties that underlie them.
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Affiliation(s)
- D C Rau
- Laboratory of Biochemistry and Metabolism, National Institute of Diabetes and Digestive and Kidney Diseases, National Institues of Health, Bethesda, MD 20892
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75
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Shatwell KP, Sutherland IW, Dea IC, Ross-Murphy SB. The influence of acetyl and pyruvate substituents on the helix-coil transition behaviour of xanthan. Carbohydr Res 1990. [DOI: 10.1016/0008-6215(90)84009-j] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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76
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On the pH-induced conformational transition of the exocellular polysaccharide from Rhizobium trifolii strain TA-1. POLYMER 1990. [DOI: 10.1016/0032-3861(90)90043-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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77
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Sato T, Kakihara T, Teramoto A. Isotropic-liquid crystal phase equilibrium in semiflexible polymer solutions: xanthan, a rigid polyelectrolyte. POLYMER 1990. [DOI: 10.1016/0032-3861(90)90041-v] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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78
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Shatwell KP, Sutherland IW, Ross-Murphy SB. Influence of acetyl and pyruvate substituents on the solution properties of xanthan polysaccharide. Int J Biol Macromol 1990; 12:71-8. [PMID: 2078534 DOI: 10.1016/0141-8130(90)90056-g] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Xanthan, an exocellular polysaccharide produced by the plant pathogenic bacterium Xanthomonas campestris has been the subject of considerable interest in recent years because of its unusual rheological properties in solution ('weak gel') and consequent range of applications. The polymer consists of a cellulosic backbone with trisaccharide side chains linked to alternate backbone residues; acetyl and pyruvate substituents are carried in variable amounts on these side chains. In this study a series of xanthans differing in the percentage of substituent groups and in molecular weight range have been prepared by culturing a variety of different strains of X. campestris. All of the xanthans have been characterized by a range of physicochemical techniques. In particular, the intrinsic viscosities at low shear rates, and at a range of ionic strengths, have been determined and the geometric persistence lengths evaluated by the Smidsrød-Haug method. Intensity light scattering measurements have been made using the procedure of Coviello and co-workers to promote molecular dispersion. Despite significant differences in the acetyl and pyruvate contents, the molecular weight vs mean square radius behaviour of our samples did not differ substantially from each other or from those reported for other xanthan samples in the literature. The persistence length, determined by the method of Schmidt et al. (120 +/- 8 nm) was also, within experimental error, the same for all the samples measured. These values differed considerably from those calculated from the ionic strength dependence of intrinsic viscosity (the Smidsrød-Haug method) was reported by Tinland and Rinaudo and calculated for our samples.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K P Shatwell
- Dept of Microbiology, University of Edinburgh, Scotland
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79
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Stokke BT, Brant DA. The reliability of wormlike polysaccharide chain dimensions estimated from electron micrographs. Biopolymers 1990; 30:1161-81. [PMID: 2085656 DOI: 10.1002/bip.360301303] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Electron micrographs of alginate, xylinan, xanthan, and scleroglucan were prepared by vacuum-drying aqueous glycerol-containing solutions, and then heavy-metal, low-angle rotary replicated. Quantitative methods for excluding streamlining effects and deformation artifacts were developed and applied to the digitized polymer contours prior to analysis of stiffness. The apparent macromolecular dimensionalities were not obtainable on the basis of the change in the scaling coefficient alpha relating the rms end-to-end distance and the contour length, mean value of r2(1/2) approximately L alpha, for chains subject to the excluded volume effect in two and three dimensions. Using a two-dimensional model, the persistence length of these molecules was estimated to be (9 +/- 1) nm (alginate), (25 +/- 4) nm (xylinan), (30 +/- 4) nm (single-stranded xanthan), (68 +/- 7) nm (double-stranded xanthan), and (80 +/- 10) nm (scleroglucan). Monte Carlo calculations for wormlike chains close to an interacting surface or confined to the region between two surfaces showed that (1) strongly adsorbed molecules are essentially two-dimensional and (2) molecules restricted to the space between two surfaces separated by a distance less than 20% of the persistence length are two-dimensional in their directional correlation. The somewhat low estimates of the persistence lengths obtained from the electron micrographs compared with those reported from solution measurements can be accounted for by the adoption of a strictly two-dimensional model in the analysis, whereas the absorbed polymers are most likely intermediate between the two-and three-dimensional cases. The model calculations and the analysis of the electron micrographs suggest that stiffness parameters are obtainable from the electron micrographs when the proper theoretical description are used in the analysis.
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Affiliation(s)
- B T Stokke
- Department of Chemistry, University of California, Irvine 92717
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80
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Shatwell KP, Sutherland IW, Ross-Murphy SB, Dea IC. Influence of the acetyl substituent on the interaction of xanthan with plant polysaccharides — I. Xanthan-locust bean gum systems. Carbohydr Polym 1990. [DOI: 10.1016/0144-8617(90)90005-d] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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81
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Fidanza M, Dentini M, Crescenzi V, Del Vecchio P. Influence of charged groups on the conformational stability of succinoglycan in dilute aqueous solution. Int J Biol Macromol 1989; 11:372-6. [PMID: 2489107 DOI: 10.1016/0141-8130(89)90010-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Viscosity, optical activity, and differential scanning calorimetry data clearly point out that partial and/or total removal of charged substituent groups, i.e. succinate and pyruvyl residues, from succinoglycan lead to water soluble derivatives exhibiting a higher stability order----disorder conformational changes with respect to the native polysaccharide. The new succinoglycan derivatives also exhibit very little, if any, hysteresis upon 'renaturation' (cooling) as opposed to the case of the parent polymer. The absence of ionized groups is thus beneficial, thermodynamically and kinetically, to the attainment in dilute aqueous solution of an ordered conformation by the uncharged succinoglycan backbone, as allowed by the regular enchainment of its constituent sugar residues.
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Affiliation(s)
- M Fidanza
- Department of Chemistry, University La Sapienza, Rome, Italy
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82
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Stokke BT, Foss P, Christensen BE, Kierulf C, Sutherland IW. Long-term storage of xanthan in seawater at elevated temperature: physical dimensions and chemical composition of degradation products. Int J Biol Macromol 1989; 11:137-44. [PMID: 2489073 DOI: 10.1016/0141-8130(89)90057-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Commercial xanthan and xanthan from Xanthomonas strain 646 produced in the laboratory have been subjected to heat treatment for various periods of time in oxygen depleted, high salinity, aqueous solutions. Both the viscosity and the carbohydrate content decreased with increasing incubation time at a specified temperature. The losses increased with increasing temperature. Data from electron micrographs and dialysable sugar content indicate that random cleavage of the double-stranded xanthan chain is the main mechanism responsible for the decreasing viscosity. Removal of pyruvate and acetate substituents on the side chains was apparently not related to the change in physical dimensions. The mannose/glucose ratio in the non-diffusible fraction decreased with incubation time, apparently not related to change in physical dimensions. Electron micrographs showed that one of the samples appeared as highly aggregated in the native condition. After 1 month at 80 degrees C, we observed that the aggregates had dissolved and that the viscosity had increased fivefold. This suggests that heat treatment can be used to avoid microgels and to obtain higher viscosifying power of the native xanthan.
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Affiliation(s)
- B T Stokke
- Institute of Physics/Institute of Biotechnology, University of Trondheim, Norway
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Kojima T, Berry G. Solution properties of xanthan. Light scattering and viscometry on dilute and moderately concentrated solutions. POLYMER 1988. [DOI: 10.1016/0032-3861(88)90119-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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87
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Liu W, Norisuye T. Order-Disorder conformation change of xanthan in 0.01M aqueous sodium chloride: Dimensional behavior. Biopolymers 1988. [DOI: 10.1002/bip.360271009] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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88
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Nakasuga M, Norisuye T. Charge-Induced Conformation Change of Xanthan in 0.01 M Aqueous Sodium Chloride. Polym J 1988. [DOI: 10.1295/polymj.20.939] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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89
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Liu W, Norisuye T. Thermally induced conformation change of xanthan: interpretation of viscosity behaviour in 0.01 m aqueous sodium chloride. Int J Biol Macromol 1988. [DOI: 10.1016/0141-8130(88)90066-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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90
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Hatakenaka K, Liu W, Norisuye T. Stability of xanthan in aqueous sodium chloride at elevated temperature. Int J Biol Macromol 1987. [DOI: 10.1016/0141-8130(87)90007-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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91
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Richardson RK, Ross-Murphy SB. Non-linear viscoelasticity of polysaccharide solutions. 2: Xanthan polysaccharide solutions. Int J Biol Macromol 1987. [DOI: 10.1016/0141-8130(87)90063-8] [Citation(s) in RCA: 112] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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