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Westberry BP, Rio M, Waterland MR, Williams MAK. On the origin of optical rotation changes during the κ-carrageenan disorder-to-order transition. Carbohydr Polym 2024; 333:121975. [PMID: 38494229 DOI: 10.1016/j.carbpol.2024.121975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 02/08/2024] [Accepted: 02/20/2024] [Indexed: 03/19/2024]
Abstract
It is well established that solutions of both polymeric and oligomeric κ-carrageenan exhibit a clear change in optical rotation (OR), in concert with gel-formation for polymeric samples, as the solution is cooled in the presence of certain ions. The canonical interpretation - that this OR change reflects a 'coil-to-helix transition' in single chains - has seemed unambiguous; the solution- or 'disordered'-state structure has ubiquitously been assumed to be a 'random coil', and the helical nature of carrageenan in the solid-state was settled in the 1970s. However, recent work has found that κ-carrageenan contains substantial helical secondary structure elements in the disordered-state, raising doubts over the validity of this interpretation. To investigate the origins of the OR, density-functional theory calculations were conducted using atomic models of κ-carrageenan oligomers. Changes were found to occur in the predicted OR owing purely to dimerization of chains, and - together with the additional effects of slight changes in conformation that occur when separated helical chains form double-helices - the predicted OR changes are qualitatively consistent with experimental results. These findings contribute to a growing body of evidence that the carrageenan 'disorder-to-order' transition is a cooperative process, and have further implications for the interpretation of OR changes demonstrated by macromolecules in general.
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Affiliation(s)
- B P Westberry
- School of Natural Sciences, Massey University, Palmerston North, New Zealand; MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, New Zealand; Fonterra Research and Development Centre, Private Bag 11029, Dairy Farm Road, Palmerston North, New Zealand.
| | - M Rio
- National Institute of Water and Atmospheric Research (NIWA), Wellington, New Zealand; Science Infrastructure (NeSI), Auckland, New Zealand
| | - M R Waterland
- School of Natural Sciences, Massey University, Palmerston North, New Zealand; MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, New Zealand
| | - M A K Williams
- School of Natural Sciences, Massey University, Palmerston North, New Zealand; MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, New Zealand
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Yang J, Kim J, Choi YJ, Hahn J. Elastic gels based on flaxseed gum with konjac glucomannan and agar. Food Sci Biotechnol 2021; 30:1331-1338. [PMID: 34721928 PMCID: PMC8519975 DOI: 10.1007/s10068-021-00977-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 08/09/2021] [Accepted: 08/23/2021] [Indexed: 10/20/2022] Open
Abstract
In this study, we prepared hydrocolloid gels in which flaxseed gum (FSG), konjac glucomannan (KGM), and agar (AG) were blended in different ratios for use as a viscoelastic food. The prepared hydrogels' physicochemical properties were analyzed concerning their water solubility index (WSI), swelling power (SL), frequency sweep results, and microstructures. As the FSG ratio decreased, the WSI value of the compound gel tended to increase. However, it showed a tendency to have a relatively high SP value and a low tan δ value according to a specific KGM/FSG/AG mixing ratios (8:2:1.5 and 6:4:1.5). Through microstructure analysis, the FKA821.5 sample showed a relatively small, monodispersed gel building structure, correlated with the rheological results. In conclusion, the FKA821.5 gel was determined to have good water retention capacity and high structural strength. These results are expected to increase the applicability of FSG-based gelling agents in the food industry.
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Affiliation(s)
- Jisoo Yang
- Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826 Korea
| | - Junghoon Kim
- Department of Food Science and Biotechnology, Sejong University, 209 Neungdong-ro, Kwangjin-gu, Seoul, 05006 Korea
| | - Young Jin Choi
- Center for Food and Bioconvergence, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826 Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826 Korea
| | - Jungwoo Hahn
- Center for Food and Bioconvergence, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826 Korea
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Koshari SHS, Wagner NJ, Lenhoff AM. Effects of Resin Architecture and Protein Size on Nanoscale Protein Distribution in Ion-Exchange Media. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:673-684. [PMID: 29286243 DOI: 10.1021/acs.langmuir.7b03289] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Knowledge of the nanoscale distribution of proteins in chromatographic resins is critical to our mechanistic understanding of separations performance. However, the nano- to mesoscale architecture of these materials is challenging to characterize using conventional techniques. Small-angle neutron scattering was used to probe (1) the nano- to mesoscale structure of chromatographic media and (2) protein sorption in these media in situ with protein-scale resolution. In particular, we characterize the effect of the architecture of cellulose-based and traditional and dextran-modified agarose-based ion-exchange resins on the nanoscale distribution of a relatively small protein (lysozyme) and two larger proteins (lactoferrin and a monoclonal antibody) at different protein loadings. Traditional agarose-based resins (SP Sepharose FF) can be envisioned as comprising long, thin strands of helical resin material around which the proteins adsorb, while higher static capacities are achieved in dextran-modified resins (SP Sepharose XL and Capto S) due to protein partitioning into the increased effective binding volume provided by the dextran. While protein size is shown not to affect the underlying sorption behavior in agarose-based resins such as SP Sepharose FF and XL, it plays an important role in the cellulose-based S HyperCel and the more highly cross-linked agarose-based Capto S, where size-exclusion effects prevent larger proteins from binding to the base matrix resin strands. Based on the data, we propose that entropic partitioning effects such as depletion forces may drive the observed protein crowding. In general, these observations elucidate the structure and point to the mechanism of protein partitioning in different classes of chromatographic materials, providing guidance for optimizing their performance.
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Affiliation(s)
- Stijn H S Koshari
- Center for Molecular and Engineering Thermodynamics, Department of Chemical and Biomolecular Engineering, University of Delaware , 150 Academy Street, Newark, Delaware 19716, United States
| | - Norman J Wagner
- Center for Molecular and Engineering Thermodynamics, Department of Chemical and Biomolecular Engineering, University of Delaware , 150 Academy Street, Newark, Delaware 19716, United States
| | - Abraham M Lenhoff
- Center for Molecular and Engineering Thermodynamics, Department of Chemical and Biomolecular Engineering, University of Delaware , 150 Academy Street, Newark, Delaware 19716, United States
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Rhein-Knudsen N, Ale MT, Ajalloueian F, Yu L, Meyer AS. Rheological properties of agar and carrageenan from Ghanaian red seaweeds. Food Hydrocoll 2017. [DOI: 10.1016/j.foodhyd.2016.08.023] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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5
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Mincer TJ, Aicher AC. Methanol Production by a Broad Phylogenetic Array of Marine Phytoplankton. PLoS One 2016; 11:e0150820. [PMID: 26963515 PMCID: PMC4786210 DOI: 10.1371/journal.pone.0150820] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Accepted: 02/19/2016] [Indexed: 11/19/2022] Open
Abstract
Methanol is a major volatile organic compound on Earth and serves as an important carbon and energy substrate for abundant methylotrophic microbes. Previous geochemical surveys coupled with predictive models suggest that the marine contributions are exceedingly large, rivaling terrestrial sources. Although well studied in terrestrial ecosystems, methanol sources are poorly understood in the marine environment and warrant further investigation. To this end, we adapted a Purge and Trap Gas Chromatography/Mass Spectrometry (P&T-GC/MS) method which allowed reliable measurements of methanol in seawater and marine phytoplankton cultures with a method detection limit of 120 nanomolar. All phytoplankton tested (cyanobacteria: Synechococcus spp. 8102 and 8103, Trichodesmium erythraeum, and Prochlorococcus marinus), and Eukarya (heterokont diatom: Phaeodactylum tricornutum, coccolithophore: Emiliania huxleyi, cryptophyte: Rhodomonas salina, and non-diatom heterokont: Nannochloropsis oculata) produced methanol, ranging from 0.8-13.7 micromolar in culture and methanol per total cellular carbon were measured in the ranges of 0.09-0.3%. Phytoplankton culture time-course measurements displayed a punctuated production pattern with maxima near early stationary phase. Stabile isotope labeled bicarbonate incorporation experiments confirmed that methanol was produced from phytoplankton biomass. Overall, our findings suggest that phytoplankton are a major source of methanol in the upper water column of the world's oceans.
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Affiliation(s)
- Tracy J. Mincer
- Woods Hole Oceanographic Institution, Department of Marine Chemistry and Geochemistry, Woods Hole, Massachusetts, United States of America
| | - Athena C. Aicher
- Woods Hole Oceanographic Institution, Department of Marine Chemistry and Geochemistry, Woods Hole, Massachusetts, United States of America
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Adsorption of peptides and small proteins with control access polymer permeation to affinity binding sites. Part II: Polymer permeation-ion exchange separation adsorbents with polyethylene glycol and strong anion exchange groups. J Chromatogr A 2012; 1227:126-37. [DOI: 10.1016/j.chroma.2011.12.092] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2011] [Revised: 12/09/2011] [Accepted: 12/27/2011] [Indexed: 11/21/2022]
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González-Ortega O, Porath J, Guzmán R. Adsorption of peptides and small proteins with control access polymer permeation to affinity binding sites. Part I: Polymer permeation-immobilized metal ion affinity chromatography separation adsorbents with polyethylene glycol and immobilized metal ions. J Chromatogr A 2012; 1227:115-25. [PMID: 22281505 DOI: 10.1016/j.chroma.2011.12.091] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 12/09/2011] [Accepted: 12/27/2011] [Indexed: 10/14/2022]
Abstract
Despite the many efforts to develop efficient protein purification techniques, the isolation of peptides and small proteins on a larger than analytical scale remains a significant challenge. Recovery of small biomolecules from diluted complex biological mixtures, such as human serum, employing porous adsorbents is a difficult task mainly due to the presence of concentrated large biomolecules that can add undesired effects in the system such as blocking of adsorbent pores, impairing diffusion of small molecules, or competition for adsorption sites. Adsorption and size exclusion chromatography (AdSEC) controlled access media, using polyethylene glycol (PEG) as a semi-permeable barrier on a polysaccharide matrix, have been developed and explored in this work to overcome such effects and to preferentially adsorb small molecules while rejecting large ones. In the first part of this work, adsorption studies were performed with small peptides and proteins from synthetic mixtures using controlled access polymer permeation adsorption (CAPPA) media created by effectively grafting PEG on an immobilized metal affinity chromatography (IMAC) agarose resin, where chelating agents and immobilized metal ions were used as the primary affinity binding sites. Synthetic mixtures consisted of bovine serum albumin (BSA) with small proteins, peptides, amino acids (such as histidine or Val⁴-Angiotensin III), and small molecules-spiked human serum. The synthesized hybrid adsorbent consisted of agarose beads modified with iminodiacetic (IDA) groups, loaded with immobilized Cu(II) ions, and PEG. These CAPPA media with grafted PEG on the interior and exterior surfaces of the agarose matrix were effective in rejecting high molecular weight proteins. Different PEG grafting densities and PEG of different molecular weight were tested to determine their effect in rejecting and controlling adsorbent permeation properties. Low grafting density of high molecular weight PEG was found to be as effective as high grafting density of low molecular weight PEG in the rejecting properties of the semi-permeable synthesized media.
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Affiliation(s)
- Omar González-Ortega
- Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, AZ 85721,USA
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Marine polysaccharides in pharmaceutical applications: an overview. Mar Drugs 2010; 8:2435-65. [PMID: 20948899 PMCID: PMC2953395 DOI: 10.3390/md8092435] [Citation(s) in RCA: 283] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 08/19/2010] [Accepted: 08/20/2010] [Indexed: 02/03/2023] Open
Abstract
The enormous variety of polysaccharides that can be extracted from marine plants and animal organisms or produced by marine bacteria means that the field of marine polysaccharides is constantly evolving. Recent advances in biological techniques allow high levels of polysaccharides of interest to be produced in vitro. Biotechnology is a powerful tool to obtain polysaccharides from a variety of micro-organisms, by controlling the growth conditions in a bioreactor while tailoring the production of biologically active compounds. Following an overview of the current knowledge on marine polysaccharides, with special attention to potential pharmaceutical applications and to more recent progress on the discovering of new polysaccharides with biological appealing characteristics, this review will focus on possible strategies for chemical or physical modification aimed to tailor the final properties of interest.
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Horger KS, Estes DJ, Capone R, Mayer M. Films of agarose enable rapid formation of giant liposomes in solutions of physiologic ionic strength. J Am Chem Soc 2009; 131:1810-9. [PMID: 19154115 PMCID: PMC2757642 DOI: 10.1021/ja805625u] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper describes a method to form giant liposomes in solutions of physiologic ionic strength, such as phosphate buffered saline (PBS) or 150 mM KCl. Formation of these cell-sized liposomes proceeded from hybrid films of partially dried agarose and lipids. Hydrating the films of agarose and lipids in aqueous salt solutions resulted in swelling and partial dissolution of the hybrid films and in concomitant rapid formation of giant liposomes in high yield. This method did not require the presence of an electric field or specialized lipids; it generated giant liposomes from pure phosphatidylcholine lipids or from lipid mixtures that contained cholesterol or negatively charged lipids. Hybrid films of agarose and lipids even enabled the formation of giant liposomes in PBS from lipid compositions that are typically problematic for liposome formation, such as pure phosphatidylserine, pure phosphatidylglycerol, and asolectin. This paper discusses biophysical aspects of the formation of giant liposomes from hybrid films of agarose and lipids in comparison to established methods and shows that gentle hydration of hybrid films of agarose and lipids is a simple, rapid, and reproducible procedure to generate giant liposomes of various lipid compositions in solutions of physiologic ionic strength without the need for specialized equipment.
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Affiliation(s)
- Kim S. Horger
- Departments of Chemical Engineering and Biomedical Engineering, University of Michigan, 1101 Beal Avenue, Ann Arbor, Michigan 48109
| | - Daniel J. Estes
- Departments of Chemical Engineering and Biomedical Engineering, University of Michigan, 1101 Beal Avenue, Ann Arbor, Michigan 48109
| | - Ricardo Capone
- Departments of Chemical Engineering and Biomedical Engineering, University of Michigan, 1101 Beal Avenue, Ann Arbor, Michigan 48109
| | - Michael Mayer
- Departments of Chemical Engineering and Biomedical Engineering, University of Michigan, 1101 Beal Avenue, Ann Arbor, Michigan 48109
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11
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Yang X, Zhu Z, Liu Q, Chen X, Ma M. Effects of PVA, agar contents, and irradiation doses on properties of PVA/ws-chitosan/glycerol hydrogels made by γ-irradiation followed by freeze-thawing. Radiat Phys Chem Oxf Engl 1993 2008. [DOI: 10.1016/j.radphyschem.2008.02.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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12
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Rinaudo M. Main properties and current applications of some polysaccharides as biomaterials. POLYM INT 2008. [DOI: 10.1002/pi.2378] [Citation(s) in RCA: 672] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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13
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Norziah M, Foo S, Karim A. Rheological studies on mixtures of agar (Gracilaria changii) and κ-carrageenan. Food Hydrocoll 2006. [DOI: 10.1016/j.foodhyd.2005.03.020] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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14
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Petrova RI, Swift JA. Selective Growth and Distribution of Crystalline Enantiomers in Hydrogels. J Am Chem Soc 2004; 126:1168-73. [PMID: 14746486 DOI: 10.1021/ja0392263] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The crystallization of sodium chlorate (NaClO3) is a classic example of spontaneous chirality, since it is achiral in solution but adopts a chiral form in the solid state. While crystal growth of NaClO3 from pure aqueous solutions yields a 50:50 statistical distribution of d- and l-crystals, large enantiomeric excesses of either d- and l-crystals can be achieved by crystal growth in agarose gel, a naturally occurring chiral polysaccharide. The influence of gel density (0.1-0.75 wt %), temperature, and the diffusion of cosolvents on crystal distribution was discerned from statistical data obtained from 752 gel-mediated crystallization experiments yielding 12,384 individual crystals. These studies demonstrate that the magnitude and direction of the bias can be selectively engineered toward either d- or l-forms by changing the gelation conditions. Aqueous agarose gels infused with 48 wt % NaClO3 at 6 degrees C, favored the growth of d-NaClO3 crystals, with ee's reaching 22% at the highest gel concentrations. Crystal growth under methanol diffusion favored deposition of the opposite enantiomorph, l-NaClO3. The bias in the crystal distribution is enhanced at higher temperatures. Aqueous gels at 24 degrees C infused with methanol cosolvent favored l-NaClO3, with ee's reaching 53%. The changing magnitude and direction of the enantiomorph bias can be ascribed to differences in the agarose conformation and intermolecular interactions between the gel and crystal surfaces that inhibit the formation of the two enantiomers to different extents.
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Affiliation(s)
- Rositza I Petrova
- Department of Chemistry, Georgetown University, 37th and "O" Streets NW, Washington, DC 20057-1227, USA
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Labropoulos K, Niesz D, Danforth S, Kevrekidis P. Dynamic rheology of agar gels: theory and experiments. Part I. Development of a rheological model. Carbohydr Polym 2002. [DOI: 10.1016/s0144-8617(02)00084-x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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16
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Kondru RK, Wipf P, Beratan DN. Structural and Conformational Dependence of Optical Rotation Angles. J Phys Chem A 1999. [DOI: 10.1021/jp990697e] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rama K. Kondru
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - Peter Wipf
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - David N. Beratan
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
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Chandrasekaran R. X-ray diffraction of food polysaccharides. ADVANCES IN FOOD AND NUTRITION RESEARCH 1998; 42:131-210. [PMID: 9597727 DOI: 10.1016/s1043-4526(08)60095-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The morphologies of food polysaccharides described in this chapter illustrate the power of x-ray fiber diffraction in conjunction with computer modeling and sophisticated refinement techniques. On the other hand, the lack of information on structures such as xanthan reflects the inadequacy of the experimental techniques used to date. But the demands from academic and industrial sectors to investigate the molecular interactions in multicomponent systems, including protein-protein, protein-polysaccharide, polysaccharide-polysaccharide, and other complexes, are high and growing, because they have important food applications. These complexes are structurally more difficult than those solved in the past 40 years and it is improbable that any chosen system will be amenable for crystallographic investigation, crystals or fibers. Modern research facilities that include two-dimensional area detectors, millisecond exposures with synchrotron x-ray radiation, interactive computer graphics, sophisticated molecular dynamics calculations, unbelievably fast and inexpensive computers, and our own intellectual abilities are indispensable tools for the future of structural science in general and food polysaccharides in particular.
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Affiliation(s)
- R Chandrasekaran
- Whistler Center for Carbohydrate Research, Purdue University, West Lafayette, Indiana 47907, USA
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Gamini A, Toffanin R, Murano E, Rizzo R. Hydrogen-bonding and conformation of agarose in methyl sulfoxide and aqueous solutions investigated by 1H and 13C NMR spectroscopy. Carbohydr Res 1997. [DOI: 10.1016/s0008-6215(97)00232-2] [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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20
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Chandrasekaran R. Molecular architecture of polysaccharide helices in oriented fibers. Adv Carbohydr Chem Biochem 1997; 52:311-439. [PMID: 9218337 DOI: 10.1016/s0065-2318(08)60094-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- R Chandrasekaran
- Whistler Center for Carbohydrate Research, Purdue University, West Lafayette, Indiana 47907, USA
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Pérez S, Kouwijzer M, Mazeau K, Engelsen SB. Modeling polysaccharides: present status and challenges. JOURNAL OF MOLECULAR GRAPHICS 1996; 14:307-21, 361-2. [PMID: 9195482 DOI: 10.1016/s0263-7855(97)00011-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The most recent tools that have been developed for modeling the three-dimensional features of polysaccharides and carbohydrate polymers are presented. The presentation starts with a description of the conformations of the monosaccharides, and of the flexible rings such as in the case of five-membered rings, and a thorough description of the conformational space that is available for a disaccharide unit, either in vacuo or in an aqueous phase. The extension to the modeling of the parent polysaccharides is addressed, based on the assumption that owing to the size and relative rigidity of the intervening monosaccharides units, the rotations at a particular linkage can be, under some conditions, considered as independent of nearest neighbor interactions. Appropriate modeling techniques are described that can provide insights into the dimensions of the chain in a solution which is best described as a random coil accompanied by the occurrence of local "helical" regions. With the help of such descriptors such as helical parameters, the ordered state of polysaccharide strands can be readily characterized. The generation of double or triple helices can be then attempted in order to explore the occurrence of such multi-stranded arrangements that may be energetically stable. The final step in the determination of the structure of polysaccharides in the ordered state, is the investigation of the interactions of different helices. This may lead to either the best arrangement(s) between two polymeric chains, or to the prediction of the dimensions, and the symmetry of a three-dimensional lattice. Some of the tools which have been developed should allow automatic scarches for meaningful correlations between structures and functions, through exploratory data analysis. Structure-function or structure-property correlation could be then used to model changes arising from structural alterations. This would open the field of polysaccharide engineering.
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Affiliation(s)
- S Pérez
- Centre de Recherches sur les Macromolécules Végétales, CNRS, Grenoble, France
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22
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Cooke D, Gidley MJ, Hedges ND. Thermal properties of polysaccharides at low moisture. ACTA ACUST UNITED AC 1996. [DOI: 10.1007/bf01992841] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Small-angle scattering from complex, hierarchically structured polymer and biopolymer networks. J Mol Struct 1996. [DOI: 10.1016/s0022-2860(96)09293-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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