Stability of Complex Carbohydrate Structures: Biofuels, Foods, Vaccines and Shipwrecks (Special Publications) - Hardcover

Hardcover

ISBN 10: 1849735638 ISBN 13: 9781849735636

Verlag: Royal Society of Chemistry, 2012

Inhaltsangabe

Complex carbohydrates such as high molecular weight polysaccharides like starch and cellulose, are well known for their importance in foodstuffs, paper and wood, but their importance extends far beyond that into the biopharmaceutical, healthcare, oil and printing industries. This book, based on a discussion meeting organised by RSC Biotechnology and Carbohydrate Groups, brings together leading experts from the polysaccharide and glycoconjugate communities to review, discuss and assess in detail one specific topic, namely the importance of the stability and degradation of carbohydrate structures. Coverage includes applications as diverse as food, biopharmaceuticals, vaccines, biofuels and preservation of Viking boats. Providing essential reading for anyone interested in these structures and the diversity of their applications, it will appeal to a broad, multidisciplinary group from industry, academia and research institutions.

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Über die Autorin bzw. den Autor

Stephen Harding has been director of the National Centre for Macromolecular Hydrodynamics for the last 24 years, a period which has seen hydrodynamic methods (analytical ultracentrifugation, light scattering, viscometry etc.) come from almost oblivion to flourish as tools for biomolecular characterisation. He has published over 350 research papers and 9 books in the field of biomolecular hydrodynamics and applied biochemistry. In recognition of his discoveries he received a junior medal from the Royal Society of Chemistry in 1991 and a DSc from the University of Oxford in 2002. In 2010 he gave the prestigious annual Pfizer lecture at the University of Connecticut and in 2012 he was awarded by King Harald V den Kongelige Norske Fortjenstorden - the Royal Norwegian Order of Merit (Knight of the 1st class) - the highest award to a foreign non Head of State. His current focus is on biopolymer stability in response to bioprocessing, of particular interest to the Biopharma industry where he now draws much of his support.

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Stability of Complex Carbohydrate Structures

Biofuels, Foods, Vaccines and Shipwrecks

By Stephen E. Harding

The Royal Society of Chemistry

Copyright © 2013 The Royal Society of Chemistry
All rights reserved.

ISBN: 978-1-84973-563-6

Contents

1 Carbohydrates: First Cousins of Water F. Franks, 1, 
2 Enzymatic Stability of Starches C.-L. Lin and R. F. Tester, 13, 
3 Enzymatic Degradation of Cell Wall Polysaccharides G.A. Tucker, 28, 
4 Functional Components and Mechanisms of Action of 'Dietary Fibre' in the Upper Gastrointestinal Tract: Implications for Health T. Grassby, C.H. Edwards, M. Grundy, P.R. Ellis, 36, 
5 Stability and Degradation Pathways of Polysaccharide and Glycoconjugate Vaccines C. Jones, 56, 
6 Mucin Turnover A.P. Corfield, 68, 
7 Viscometry, Analytical Ultracentrifugation and Light Scattering Probes for Carbohydrate Stability S.E. Harding, 80, 
8 Stability of Pectin-Based Drug Delivery Systems G.A. Morris, G.G. Adams, S.E. Harding, J.D. Castile and A. Smith, 99, 
9 Stability of Polysaccharide Complexes: The Effect of Media and Temperature on the Physical Characteristics and Stability of Chitosan-Triphosphate/Alginate Nanogels C.A. Schiitz, P. Käuper and C. Wandrey, 110, 
10 Cellulose Crystallinity: Perspectives from Spectroscopy and Diffraction M. C. Jarvis, 125, 
11 The Water Vapour Sorption Properties of Cellulose C.A.S. Hill and Y. Xie, 137, 
12 Lignin Biosynthesis and Lignin Manipulation P. Daly, M. Maluk, M. Zwirek and C. Halpin, 153, 
13 Bacterial degradation of Archaeological Wood in Anoxic Waterlogged Environments N.B. Pedersen, C.G. Bjordal, P. Jensen and C. Felby, 160, 
Subject Index, 188, 

CHAPTER 1

CARBOHYDRATES: FIRST COUSINS OF WATER

F. Franks

BioUpdate Foundation, 25 The Fountains, Ballards Lane, London N3 1NL asdi35@dsl.pipex.com

1 INTRODUCTION

Water has frequently been described as the most eccentric molecule in our ecosphere. Its many anomalous physical properties derive basically from the sp3 hybridisation of the oxygen orbitals, which gives rise to an almost tetrahedral, quadrupolar bond orientation, in which the oxygen atom is placed at the centre of the water tetrahedron and four charges, two -OH groups (positive) and two lone electron pairs (negative) are directed towards the vertices, as shown in Figure 1. That, in itself, is not a unique molecular feature; for instance SiO2 and GeO2 have similar tetrahedral configurations. The unique features of H2O are twofold: 1) its inability to form or participate in stable covalent bonds. Hydrogen bonding is thus the only method by which the molecule can interact with other molecules, including other water molecules, and 2) because of its quadrupolar nature with an equal number of proton donor and acceptor sites, H2O is thus amphipathic, and as such, it can participate in a wide range of reactions: proton donor/acceptor, oxidation/reduction, and hydrolysis/aggregation. To some extent, carbohydrates are able to participate in the same types of reactions, although the rates in fused (vitreous) carbohydrates will differ vastly from those in liquid aqueous solutions.

The description of molecules composed of C, H and O as 'carbohydrates' provides a clue for some of their properties that are of particular significance to their industrial and medical applications. Another generic description is polyhydroxy compounds (PHC), which provides a further clue – water sensitivity/miscibility – to their usefulness. Added to this are their diverse functions in life processes, providing structures, energy storage, metabolic intermediates, recognition and defence (immune) systems and much else. The generic formula of many simple PHC compounds, when written as [FORMULA OMITTED], also suggests a close relationship between water and PHC molecules. Indeed, any material in our ecosphere that is composed mainly of C, H and O is either miscible with water, or at least sensitive to water, so that dry (anhydrous) organic materials do not exist in nature. Water has been described as the 'ubiquitous plasticizer' for all organic matter.

The actual relationship between water and PHCs at the molecular level lies in their almost identical oxygen orbital hybridization: -OH groups of the organic molecules structurally and energetically resemble those of water, i.e. in their interactions they are limited to hydrogen bonding and their bond orientations are also in the form of a tetrahedron. It indicates that PHC molecules in their crystalline state closely resemble ice and are held together (or apart) by weak interactions and, like ice, they can form chains, rings and infinite three dimensional networks. In their crystalline states they can also interact with water in the form of stoichiometric hydrates, e.g. glucose. H2O,α,α-trehalose.2H2O, β, β-trehalose.4H2O, raffmose.5H2O. Like inorganic hydrates, for example [Na.sub.2]C[O.sub.3].10[H.sub.2]O, they should be able to be dehydrated to lower hydration states and finally to anhydrous crystals, but unlike their inorganic counterparts, most of these hypothetical solid/solid transitions take place very slowly and proceed via long-lived non-crystalline (amorphous) intermediate states; characteristic transition temperatures cannot therefore be easily observed. Their phase transitions usually take place over very extended periods (months or years), and very few such systems have actually been studied directly in 'real time'. Therefore, the dehydrations appear to be irreversible in real time, so that the mixtures may consist of the higher and lower hydration states and the released water. The mixture will thus remain thermodynamically unstable and maintain an apparent stability due to exceedingly slow molecular motions, in the order of mm/century, until a spontaneous devitrification to the more stable, crystalline state, e.g. during annealing, occurs and is accompanied by more or less severe changes in their mechanical properties, such as tensile or torsional strength. Examples of such spontaneous devitrifications readily occur in metal alloys, in the crystallisation of cholesterol from its highly supersaturated solution in the gall bladder, or in the crystallisation of lactose in ice cream. The results may be of different orders of severity, ranging from loss of life to physical pain and minor inconvenience. Thus, several of the first ever jet-engined commercial airliners, the de Havilland Comet, disappeared during long-haul flights, when the fuselage disintegrated, resulting from metal stress and subsequent devitrification. The nucleation and biocrystallisation of cholesterol in the gall bladder results from a chemically minor error in the biosynthesis of bile salt molecules, whose natural function is the prevention of cholesterol precipitation from its supersaturated solution. The possibility of random devitrification of lactose in some cartons of ice cream, even during frozen storage, is still a subject of research.

Other possible sources of PHC dehydration problems include the decomposition of a previously unknown PHC hydrate, especially in pharmaceutical formulations, where such release of water during processing, e.g. mannitol. H2O -> mannitol + H2O, can result in major stability losses in the drug product. With our present sketchy knowledge of the close relationship between water and the hydrogen bond topology of PHCs, it is likely that more such presently unknown hydrates remain to be discovered.

It is also likely that future experimental data on crystalline PHC...

Details zur Ausgabe

• Verlag: Royal Society of Chemistry
• Erscheinungsdatum: 2012
• Sprache: Englisch
• ISBN 10: 1849735638
• ISBN 13: 9781849735636
• Einband: Gebundene Ausgabe
• Anzahl der Seiten: 195
• Herausgeber: Harding Stephen E.
• Kontakt zum Hersteller: Nicht verfügbar
• Verantwortliche Person: Nicht verfügbar