Chemistry
Oligosaccharides
Oligosaccharides are carbohydrates composed of a small number of monosaccharide units, typically 3 to 10. They play important roles in cell recognition, immune response, and as energy sources. Oligosaccharides are found in foods such as legumes, whole grains, and certain fruits and vegetables, and are also used in various industrial applications.
Written by Perlego with AI-assistance
Related key terms
1 of 5
10 Key excerpts on "Oligosaccharides"
eBook - PDFCarbohydrate Chemistry
Monosaccharides and Their Oligomers
- Hassan El Khadem(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
II Oligomeric Saccharides: Oligosaccharides and Nucleotides This page intentionally left blank 6 Structure of Oligosaccharides Oligosaccharides are polymeric saccharides that have, as their name denotes, a low degree of polymerization (oligos means f e w in Greek). They are composed of 2-10 glycosidically linked monosaccharides, which can be liberated by depolymerization (for example, by acid hydrolysis). Oligosaccharides having degrees of polymerization of 2-3 are sweet in taste and are included among sugars, whereas higher members are devoid of taste and are not referred to as sugars. Oligosaccharides are grouped into simple (or true) Oligosaccharides, which on depolymerization yield monosaccharides only, and conjugate Oligosaccharides, which are linked to such nonsaccharides as peptides and lipids and on depolymerization yield monosaccharides and aglycons. The simple Oligosaccharides are further classified according to (a) degree of polymerization, into disaccharides, trisaccharides, tetrasaccharides, etc.; (b) whether they are composed of one or more types of monosac-charides, into homo- and hetero-Oligosaccharides; and finally (c) whether they do or do not possess a hemiacetal function at one terminus of the molecule, into reducing and non-reducing Oligosaccharides. Related homo-Oligosaccharides can form homologous series; a homolo-gous series of Oligosaccharides is a group of similarly linked oligosac-charides that are composed of the same monomer, and whose degree of polymerization increases in the series by one unit at a time. When homo-polysaccharides are partially hydrolyzed, they often yield homologous 191 192 6. Structure of Oligosaccharides series of Oligosaccharides. For example, the malto-Oligosaccharides ob-tained by partial hydrolysis of starch comprise dimers, trimers, tetramers, etc., composed of α -D -glucopyranosyl units linked by (1 -» 4) glycosidic bonds.
eBook - PDF- Dmitry Murzin, Olga Simakova(Authors)
- 2015(Publication Date)
- Royal Society of Chemistry(Publisher)
CHAPTER 6 Oligosaccharides for Pharmaceutical Applications JANI RAHKILA, TIINA SALORANTA AND REKO LEINO* Johan Gadolin Process Chemistry Centre, c/o Laboratory of Organic Chemistry, Åbo Akademi University, FI-20500 Åbo, Finland *Email: [email protected] 6.1 Introduction Carbohydrates are the most abundant biomolecules on earth with functions ranging from the fundamental building block of RNA (ribose) to the most important energy store of human bodies (glucose). The latter is also the building block of cellulose, the most abundant biopolymer on earth. Com-pared to proteins, which consist of amino acids connected in a linear fashion, carbohydrate arrays are often branched with the monosaccharides connected to each other in various ways giving them great potential for storage of biological information. For example, a simple disaccharide con-sisting of only two hexopyranose moieties can be constructed in 11 different ways. Upon moving to larger Oligosaccharides, the number of permutations increases exponentially. While not all possible combinations of mono-saccharides exist in nature, the number of different Oligosaccharides avail-able by contemporary synthetic methods allows for a high degree of customization. This, in turn, results in highly specific binding achievable by fine-tuning of the three-dimensional structure of carbohydrates to match the binding sites of biological receptors. If the binding site is known, carbo-hydrates can be designed to match in an optimal, specific way. Transport of the carbohydrate systems to their active sites is, however, not trivial. Due to RSC Green Chemistry No. 44 Biomass Sugars for Non-Fuel Applications Edited by Dmitry Murzin and Olga Simakova r The Royal Society of Chemistry 2016 Published by the Royal Society of Chemistry, www.rsc.org 205 the usually high polarity of the carbohydrate molecules, they are unable to efficiently pass through the enterocyte layer of the small intestine.
eBook - PDF- Jose Perez-Castineira(Author)
- 2020(Publication Date)
- De Gruyter(Publisher)
– Sugar: Many monosaccharides and disaccharides are sweet, hence their trivial name sugars, although table sugar is only composed of sucrose, a disaccha- ride. Carbohydrates are also known as glycids (from the Greek glykys, glykeros: sweet) or saccharides (from the latin saccharum: sugar). – Polysaccharides: Polymers composed of more than 12 (or 20) residues of mono- saccharides. Polysaccharides are named as homo- or heteropolysaccharides depending on whether they are composed of a single type or more than one type of monosaccharide, respectively. Oligo- and polysaccharides can be linear or branched and they may undergo further chemical modifications (see below). – Glycan: Although this term is considered a synonym of polysaccharide by the IUPAC [2], biochemists use it for those oligo- or polysaccharides that bind to other biomolecules. – Glycoconjugates: Biochemical compounds consisting of a glycan moiety linked to proteins or lipids. The process by which a glycan is attached to another bio- molecule is known as glycosylation when it is catalyzed by an enzyme, or https://doi.org/10.1515/9783110595482-003 glycation when it is just a chemical non-mediated process. There are several types of glycoconjugates: – Glycoproteins/glycopeptides: Proteins/peptides (Chapter 5) containing oligosaccharide chains covalently attached to amino acid side chains. – Peptidoglycans: Generally composed of linear heteropolysaccharides cova- lently linked with short peptides. – Glycolipids: Lipids (usually 1,2-diacylglycerols, see Chapter 4) with a monosaccharide or oligosaccharide linked. – Lipopolysaccharides: Complex glycolipids that occur in the outer mem- brane of Gram-negative bacteria. They induce immune response in many species, including humans.
eBook - PDF- Peter Grunwald(Author)
- 2011(Publication Date)
- Jenny Stanford Publishing(Publisher)
Chapter 3 Oligosaccharides AND GLYCOCONJUGATES IN RECOGNITION PROCESSES Thisbe K. Lindhorst Otto Diels Institute of Organic Chemistry, Christiana Albertina University of Kiel, Otto-Hahn-Platz 3/4, D-24098 Kiel, Germany [email protected] 3.1 INTRODUCTION All cells, eukaryotic cells in particular, are covered with carbohydrates of enormous diversity. These are part of different glycoconjugates, which are embedded into the lipid bilayer of the plasma membrane or associated to the glycocalyx of the cell. The glycocalyx is a highly complex sugar coating, which is typical and important for every eukaryotic cell. It can be considered to form an interconnecting supramolecular entity between the extracellular matrix and the cytoskeleton and, apparently, is an indispensable “cell organelle.” Saccharides are major constituents of the glycocalyx, playing an essential role in cell biology. This is well-known for the famous blood group antigens of red blood cells, all of them being carbohydrates. The biological significance of cell surface carbohydrates in cell communication unfolds in a highly complex interplay with other Carbohydrate-Modifying Biocatalysts Edited by Peter Grunwald Copyright © 2012 Pan Stanford Publishing Pte. Ltd. www.panstanford.com 120 Oligosaccharides and Glycoconjugates in Recognition Processes molecules, both membrane-anchored receptors and soluble molecules. There are secreted or membrane-bound proteins, which can recognize carbohydrates to form carbohydrate–protein complexes that are involved in cell development, the immune system, signal transduction, and also states of disease and malignancy. These proteins are called the lectins and occur ubiquitously in all organisms. Intracellular lectins frequently recognize core structures from glycoconjugate Oligosaccharides, while cell surface and extracellular lectins often bind to terminal carbohydrate residues.
eBook - PDF- Daniel E. Levy, Péter Fügedi, Daniel E. Levy, Peter Fügedi(Authors)
- 2005(Publication Date)
- CRC Press(Publisher)
204 5.5.3 Polymer-Supported and Solid-Phase Oligosaccharide Synthesis ............................. 208 5.6 Summary and Outlook ........................................................................................................ 214 References ................................................................................................................................... 216 5.1 INTRODUCTION It is now well established that glycoconjugates play essential roles in a variety of biological processes, including fertilization, embryogenesis, cell proliferation and cell adhesion [1,2]. Changes in carbohydrate structures are also associated with disease states. The remarkable changes in cell surface carbohydrates that occur during tumor progression are of notable importance. The biological activities that carbohydrates play in these processes are typically linked not to monosaccharide units, but to oligosaccharide structures of glycoconjugates. Just as in the fields of nucleic acids and peptides, the synthesis of Oligosaccharides is an essential tool in studying the biochemistry and biology of vital processes. Compared with other natural oligomers, such as peptides and oligonucleotides, oligosacchar-ides have much greater structural diversity. Aside from the number of monomers, the differences in anomeric configuration, ring size and, especially, the possibly different attachment points of the monomers (including the occurrence of branched structures) dramatically increase the diversity of Oligosaccharides.
- Jack Rosenfeld(Author)
- 2009(Publication Date)
- Wiley-Blackwell(Publisher)
5 Oligosaccharides H ´ EL ` ENE PERREAULT 5.1 Introduction Carbohydrates are best and popularly known known as a food source for most organ-isms. Biologists, biochemists and chemists, however, recognize that they also serve as structural materials for plants and are involved in many other, frequently complex, biological functions. They take part in these functions when coupled to other classes of molecules with the combination being termed glycoconjugates. Protein glycosylation describes important relationships between proteins and Oligosaccharides. It is one of the most important processes among all types of post-translational modifications [1] and produces a wide spectrum of biologically important molecules [2]. Investigation of the structure and function of glycoproteins is an active area of re-search, and the functional significance of the carbohydrate moieties has become in-creasingly apparent [3]. Glycoproteins encompass several important classes of macro-molecules, including enzymes, hormones, immunoglobulins, transport proteins, cell adhesion molecules, and cytoplasmic proteins [2]. The roles of protein-bound carbohy-drates in biological recognition, such as in host–pathogen, cell–cell and cell–molecule interactions generate considerable interest and investigation. Clearly, elucidating the structure of various glycoproteins is an essential component of current biological study and constitutes a large part of the field of glycomics. In conjunction with genomics and proteomics, glycomics forms a triad of disciplines that investigate the structure and function of biological macromolecules. This triad holds great promise in advancing the understanding of biology and in the application of this knowledge to human welfare. Although much remains to be discovered, there already exists knowledge about gly-cosylation of proteins. Generally, each glycosylation site on a protein bears different, although related, glycans, a phenomenon called microheterogeneity.
eBook - PDFPenta- and Higher Polyhydric Alcohols, Their Oxidation Products and Derivatives, Saccharides
A Modern Comprehensive Treatise
- S. Coffey(Author)
- 2013(Publication Date)
- Elsevier(Publisher)
Chapter 24 Oligosaccharides, Polysaccharides and Related Compounds G. 0. A S P I N A L L , E. P E R C I V A L , D. A. R E E S and M. R E N N I E The more complex saccharides, i.e. those containing two or more sugar residues joined by glycosidic linkages, are termed ohgosaccharides. Although the precise upper limit to the number of sugar residues has not been rigorous-ly defined for this class of compounds, ohgosaccharides containing up to six or seven sugar residues have been characterised. In the case of the Schardinger dextrins (see p. 682) discrete substances containing up to ten residues have been isolated and identified. In the following discussion attention will be directed chiefly to the disaccharides but similar consider-ations apply in the study of the higher members. Ohgosaccharides containing more than ten sugar residues are usually classed separately as polysaccharides (see p. 664). The unique determination of the structures of these compounds and the less complex higher ohgosaccharides presents similar problems, especially with regard to establishing the exact sequences of the sugar units. At the end of the chapter brief accounts are given of the following natural products which are related to the ohgosaccharides : (a) the teichoic acids, polymers of glycerol or ribitol phosphates; (b) the glycoproteins and (c) the glycohpids. 1. Ohgosaccharides* Classification. Di- and higher ohgosaccharides are divided into two main groups, those which contain one free reducing group per molecule, and those in which all the potential reducing groups are involved in glycosidic linkages. These classes are exemplified by the reducing disaccharide maltose (I) and the non-reducing disaccharide sucrose (II). Reducing disaccharides are * See also R. W. Bailey, Oligosaccharides, Pergamon Press, Oxford, 1965. I Oligosaccharides 597 so-called because of their action on various reagents, e.g.
eBook - PDF- F. Korte(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
3 Oligosaccharides A large number of Oligosaccharides have been isolated from natural sources and their structures have been elucidated 3,7,9 . In order to determine the structure of an oligo-saccharide, the following information must be obtained: molecular size, identity and sequence of sugar components, type of ring structures, position of linkages and stereochemical con-79 /. R. Turvey, Advan. Carbohyd. Chem. 20, 183 (1965). 80 7. R. Turvey, D. A. Rees, Nature 189, 831 (1961). 81 D. A. Rees, J. Chem. Soc. 1821 (1963). 82 /. Love, E. Percival, J. Chem. Soc. 3338 (1964). 83 E. L. Hirst, W. Mackie, E. Percival, J. Chem. Soc. 2958 (1965). 84 K. Anno, N. Seno, M. Ota, Carbohyd. Res. 13, 167 (1970). 88 /. R. Turvey, D. M. Bowker, M. J, Harris, Chem. Ind. (London) 2081 (1967). 86 S. Peat, D. M. Bowker, J. R. Turvey, Carbohyd. Res. 7, 225 (1968). 87 V. P. Bhavanandan, K. Meyer, Science 151, 1404 (1966). 169 3.1:3.1 Oligosaccharides Containing Neutral Sugars Only figuration of the glycosidic linkages. The reduc-ing end unit of an oligosaccharide is usually determined by analysis after reduction with sodium borohydride. Determinations of the ring form and the linkage of each constituent unit are most frequently achieved by periodate oxi-dation or methylation analysis. The permethyla-tion of Oligosaccharides is effectively carried out with methyl iodide in the presence of methyl-sulfinyl carbanion 88 · 89 . The degree of polymeriza-tion can be determined by the colorimetric method 90 or gas chromatography 91 after reduc-tion and hydrolysis. Specific rotation values of products from periodate and lead tetraacetate oxidation have been found to correlate with the configuration of the glycosidic linkage of oli-gosaccharides 92 . Infrared spectra and especially nuclear magnetic resonance spectra provide use-ful information on the configuration of glycosidic linkages.
eBook - PDFBiotemplating: Complex Structures From Natural Materials
Complex Structures from Natural Materials
- Simon Robert Hall(Author)
- 2009(Publication Date)
- ICP(Publisher)
The simplest monosaccharides have found little use in biotemplating owing to their inability to form extended complex structures of their own volition. Of slightly more use are the simple Oligosaccharides as they are able to chelate ions more readily and to begin to form complex macromolecular structures of their own. There have been Simple Mono- and Oligosaccharides 15 a few examples where mono- and Oligosaccharides have been used and it is on these that this chapter will concentrate. Figure 2.1 – Molecular representation of the structure of fructose. Di- and Oligosaccharides are simply composed of monosaccharide units (typically 2 to ten) joined together, usually through a condensation reaction forming a glycosidic bond (Figure 2.2). Figure 2.2 – A molecule of sucrose with the glycosidic bond indicated. As any of the hydroxyl groups on each component sugar unit can form the glycosidic bond, there exists the potential for a huge range of isomers of even very simple Oligosaccharides. Differences in stereochemistry in the disaccharides can result in isomers with very different physical and chemical properties. In addition, as they contain aldehyde or ketone groups, the mono-, di- and 16 Biotemplating Oligosaccharides are able to take part in simple chemical reactions. For example, reduction of glucose gives an alcohol and mild oxidation gives a carboxylic acid, typical behaviour for compounds containing an aldehyde group. This limits their use as templates for inorganic mineralization, as many inorganic phases are subject to reduction when saccharides are present. Conversely, it is just this sort of activity that can be used in a synthesis to arrive at the reduced form of a desired mineral. 2.2 Use as a source of carbon As a biotemplate, the mono- and Oligosaccharides are most frequently used as a convenient source of carbon, either through chemical oxidation by acids, or by the action of heat in inert gas environments.
eBook - PDF- J. B. Harborne(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
5 Oligosaccharides P. M. DEY Department of Biochemistry, Royal Holloway and Bedford New College, University of London, Eg ham, Surrey TW20 OEX, UK I. Introduction 189 II. Trisaccharides 191 A. Umbelliferose 191 B. Raffinose 194 C. Planteose 200 D. Other trisaccharides 201 III. Tetrasaccharides 202 A. Stachyose 202 B. Lychnose 206 C. Isolychnose 207 D. Sesamose 208 E. Other tetrasaccharides 209 IV. Higher homologues 210 A. Stachyose series 210 B. Sesamose series 211 C. Lychnose series 212 D. Isolychnose series 213 V. Concluding remarks 214 References 215 I. INTRODUCTION The D-galactose-containing Oligosaccharides that occur in free form will be the main subject of discussion in this chapter. Of these, the α-galactosyl derivatives of sucrose are METHODS IN PLANT BIOCHEMISTRY Vol. 2 Copyright © 1990 Academic Press Limited ISBN 0-12-461012-9 All rights of reproduction in any form reserved 189 190 P. M. DEY the most commonly occurring members in the plant kingdom. A general survey reveals that these are the most abundant soluble sugars in plants and rank only second to sucrose. These sugars are the primary Oligosaccharides and are synthesised in vivo. In contrast, the secondary Oligosaccharides are those which are derived by enzymic degradation of higher homologous Oligosaccharides, heterosides and polysaccharides. One physiological function of the galactosyl Oligosaccharides is as reserve carbohy- drates in storage organs such as seeds and tubers. They are mobilised during the early stages of germination (see Dey, 1985). They are therefore synthesised and deposited in these organs during the maturation process. It is also conceivable that a fraction of these Oligosaccharides arrive at this location as translocated material.
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
