Table Of ContentPOLYSACCHARIDES
TOPICS IN
MOLECULAR
AND STRUCTURAL
BIOLOGY
General Editors:
Watson Fuller
(University of Keele)
and
Stephen Neidle
(University of London
King's College)
POLYSACCHARIDES
Topics in Structure and Morphology
Edited by
E. D. T. ATKINS
Professor of Physics and Science
and Engineering Research Council Senior Fellow
H. H. Wills Physics Laboratory
University of Bristol
M
MACMILLAN
© The contributors 1985
Softcover reprint of the hardcover 1st edition 1985
All rights reserved. No reproduction, copy or transmission
of this publication may be made without written permission.
No paragraph of this publication may be reproduced, copied
or transmitted save with written permission or in accordance
with the provisions of the Copyright Act 1956 (as amended).
Any person who does any unauthorised act in relation to
this publication may be liable to criminal prosecution and
civil claims for damages.
First published 1985
Published by
THE MACMILLAN PRESS LTD
Houndmills, Basingstoke, Hampshire RG21 2XS
and London
Companies and representatives
throughout the world
Typeset by TecSet Ltd,
Sutton, Surrey
British Library Cataloguing in Publication Data
Atkins, Edward
Polysaccharides.-(Topics in molecular and
structural biology)
1. Polysaccharides
I. Title II. Series
547.7'82 QD321
ISSN 0265-4377
ISBN 978-1-349-06371-0 ISBN 978-1-349-06369-7 (eBook)
DOI 10.1007/978-1-349-06369-7
The contributors
Margaret Biswas W. Mackie
Molecular Biophysics Unit Astbury Department of Biophysics
Indian Institute of Science University of Leeds
Bangalore-560012 Leeds LS2 9JT
India UK
Benito Casu I. A. Nieduszynski
lstituto di Chimica e Department of Biological Sciences
Biochimica 'G. Ronzoni' University of Lancaster
Via G. Colombo 81 (Citta Studi) Bailrigg
20133-Milan Lancaster LAl 4TQ
Italy UK
H. Chanzy V. S. R. Rao
Centre de Recherches sur les Molecular Biophysics Unit
Macromolecules V egetales (CNRS) Indian Institute of Science
53X-38041 Bangalore-560012
Grenoble Cedex India
France
R. Vuong
D. H. Isaac Centre de Recherches sur les
Department of Metallurgy and Macromolecules Vegetales (CNRS)
Materials Technology 53X-38041
University College Swansea Grenoble Cedex
Singleton Park France
Swansea SA2 8PP
UK
Contents
The contributors v
Preface ix
1. NUCLEAR MAGNETIC RESONANCE STUDIES OF
POLYSACCHARIDE STRUCTURE AND INTERACTIONS
B. Casu
2. ULTRASTRUCTURE AND MORPHOLOGY OF CRYSTALLINE
POLYSACCHARIDES H. Chanzy and R. Vuong 41
3. PLANT CELL WALLS: MORPHOLOGY, BIOSYNTHESIS AND
GROWTH W. Mackie 73
4. CONNECTIVE TISSUE POLYSACCHARIDES
l A. Nieduszynski 107
5. BACTERIAL POLYSACCHARIDES D. H. Isaac 141
6. CONFORMATIONS AND INTERACTIONS OF
OLIGOSACCHARIDES RELATED TO THE ABH AND
LEWIS BLOOD GROUPS V. S. R. Rao and Margaret Biswas 185
Index 219
Preface
Carbohydrate molecules are ubiquitous in nature. The structures and textures
of terraqueous plants are dominated by polysaccharides such as cellulose,
mannan, alginate, pectin and xylans. Chitin plays a major structural role in insect
cuticle, usually blending with proteins and interacting with crystalline inorganic
salts in an analogous manner to the calcification of collagen in bone. In animal
tissues, polysaccharides such as hyaluronate, chondroitin and dermatan sulphates
function as lubricants, gels, compliant matrices and also exhibit visoelastic
properties. Their polyelectrolytic character responds to different cations, changes
in ionic strength and degree of hydration to produce conformational variability.
Many bacteria are encapsulated with swollen polysaccharide networks with
particular species often displaying numerous serotypes, each with its own sig
nature in the form of a precisely defined covalent repeating structure. There are
many instances where carbohydrates are covalently attached to proteins to form
proteoglycans and glycoproteins, and which serve as vital functional operators
in molecular biology. The blood group substances are delineated by their carbo
hydrate components, and cell surfaces are decorated with polysaccharides such
as heparan sulphate, which influence cell adhesion and recognition. The poly
saccharide heparin suppresses blood clotting and certain glycoproteins act at
antifreeze agents in the blood of polar fish. These examples, which are part of
a spectrum of occurrences, properties and functions of polysaccharides and
carbohydrate polymers, highlight the importance of this group of macro
molecules in the natural world.
Advances in the biomolecular structure of carbohydrate polymers have been
more recent and have had less popular impact than the parallel developments in
the protein and nucleic acid field. However, during the last fifteen years steady
progress has been made in our understanding of a wonderful world of shapes,
geometries and architecture of this important group of macromolecules. This
text describes the application of nuclear magnetic resonance, electron micro
scopy, X-ray fibre diffraction and conformational analysis to certain plant,
animal and microbial polysaccharides and carbohydrate polymers.
The first chapter is concerned with the application of nuclear magnetic
resonance (n.m.r.) spectroscopy to polysaccharide structure and interactions.
This technique is a most effective method for investigating structure, dynamics
and binding properties of polysaccharides. It has the potential to follow patterns
X PREFACE
of interaction from solution into the condensed phase and offers exciting pros
pects for future advances in our understanding of polysaccharide behaviour. A
comprehensive review and literature survey are given of the application of n.m.r.
to many aspects of polysaccharide structure and interaction.
The next chapter focuses attention on the texture, morphology and ultra
structure of crystalline polysaccharides using electron microscopy and electron
diffraction. Delightful textures in the form of extended-chain crystals overlaid
with lamellar platelets to form a 'shish-kebab' morphology, are convincingly
visualised. Biological polymers are extremely sensitive to electron-beam damage
and crystallinity is easily destroyed. Methods of examining hydrated specimens
using quench-freeze techniques are described and numerous high-quality patterns
illustrated. Progress in the visualisation of polysaccharide hydrogels is discussed
and examples of the results obtained are shown in order to provide the reader
with a feel for the current state of the art.
Chapter 3 reviews the morphology, biosynthesis and growth of plant cell
walls with emphasis on the polysaccharide components. Much of the plant
world is dominated by composite structures consisting of cellulose microfibrils
interacting with less crystalline non-cellulosic polysaccharides capable of fabri
cating a variety of molecular architectures. In algae, mannan and xylan can
replace cellulose as the microfibrillar component. The development and growth
of plant cell walls is an intriguing subject and this chapter reviews the current
level of our understanding.
Chapter 4 reviews the molecular shapes, and the interactions of the connective
tissue polysaccharides or glycosaminoglycans. These polysaccharides were first
crystallised in a tangible form in the early 1970s and the results obtained have
encouraged considerable interest and activity in the molecular biology of poly
saccharides. Their polyelectrolyte character has added a further dimension to
their versatility in conformation and interactions. X-ray diffraction, and more
recently n.m.r. spectroscopy, have provided important insights into their design
and patterns of behaviour. Changes in puckered-ring structures occur as a function
of hydration and ionic environment. They bind to proteins to create exceedingly
complex and hierarchical proteoglycan structures.
Chapter 5 reviews the polysaccharides produced by bacteria. These bio
polymers have quite complex repeating sequences (up to six or so different
saccharide residues per repeat) and glycosidic linkage geometries: some are linear
and others have side branches. It is only in recent years that the commercial
potential of these polysaccharides has been appreciated and that the exploitation
of micro-organisms as polysaccharide producers using continuous fermentation
techniques has been given serious consideration. Most of the conformations
described in this chapter have only been investigated within the last ten years.
The Klebsiella serotypes have so far provided the most comprehensive glimpse
of variations in polysaccharide conformation using X-ray fibre diffraction and
computer modelling procedures. These polysaccharides highlight the variety of
geometries generated by variation of glycosidic linkage.
PREFACE xi
The final chapter discusses the shapes and interactions of the blood-group
related oligosaccharides. It has not yet been possible to crystallise these sub
stances but the preferred shapes can be generated using computer modelling
procedures and energy minimisation. The oligosaccharides are usually bifurcated
and attached to a polypeptide chain at a serine or threonine residue. The three
dimensional shapes generated are introduced into the known active site regions
of antibodies. Changes in specific saccharide units can have important conse
quences for binding.
I sincerely hope that this selection of topics, covering many aspects of the
structural molecular biology of polysaccharides, will encourage others to interest
themselves in carbohydrate polymers. I thank the contributors for providing
concise and authoritative reviews of their subject matter.
Bristol, July 1985 E.D.T.A.
