Oligosaccharides and Polysaccharides

The lectins can be conveniently divided into the legume (Fabaceae family) and nonlegume proteins. The legume lectins are exemplified by the homodimeric or homo-tetrameric, Ca2+- and Mn2+-binding and mitogenic protein concanavalin A (jackbean phytagglutinin) from Canavalia ensiformis that binds Man, Glc and Man-al-Me. 

A further subset of lectins is comprised of those lectins associated with type 2 RIP lectin-PAG complexes (see Chapter 9). The lectin moiety targets the toxic lectin-PAG complex to the plasma membrane, thus permitting PAG entry and target cell death through ribosome inactivation and inhibition of protein synthesis (see Chapter 9). 

Plants also produce structurally related enzymes (chitinases) that catalyse the hydrolysis of chitin (Table 12.2) and hence damage chitin-based insect integuments. Class I chitinases are basic enzymes with an jV-terminal hevein-related CBD and vacuole-targeting C-terminal signals whereas Class II enzymes are acidic proteins lacking these CBD and vacuole-targeting domains. Class IV chitinases are variously basic and acidic extracellular proteins with 

Miscellaneous Polysaccharides and Oligosaccharides.—The reaction of acidic polysaccharides with cetyltrimethylammonium bromide has been studied by recording the turbidity with an automatic titration device. The optimal conditions for the quantitative determination of various acidic polysaccharides were found from a correlation between ionic strength and turbidity. 

A crude D-glucose- and 2-acetamido-2-deoxy-D-glucose-containing polysaccharide from Aspergillus niger has been adsorbed (1 1) on diatomaceous earth and used for affinity chromatographic purification of the lectins from Datura stramonium.  

Free monosaccharides can be used for direct glycosylation of Spheron , a spherical macroporous hydroxyalkyl methacrylate-ethylene dimethacrylate co-polymer. Derivatives of L-fucose, o-galactose, D-glucose, D-mannose, 2-acetamido-2-deoxy-D-galactose, and 2-acetamido-2-deoxy-D-glucose have been prepared in this way and shown to be efficient affinity carriers for the isolation of a number of lectins. 

Hydrophilic, water-insoluble gels suitable for affinity chromatography of lectins have been prepared by co-polymerization of acrylamide, A, JV -methylene-bis-acrylamide, and alkenyl-1-thioglycosides, and used for purification of 

HofejSi, P. Smolek, and J. Kocourek, Biochim. Biophys. Acta, 1978, 538, 293. 

Blood-group A substance has been partially deacetylated with toluene-p-sulphonic acid. The deacetylated product reacted with a cyclic imidocarbonate derivative of agarose cross-linked with 2,3-dibromopropanol to give a material used as an immunoadsorbent for anti-(blood-group A) antibodies. 

Milk oligosaccharides coupled to poly(L-lysine) by a mixed anhydride procedure were shown to be effective precipitating antigens. The conjugate 

The reactivity of a polysaccharide containing D-glucopyranosyl and o-altro-pyranosyl residues to acetylation, etherification, hydrolysis, and nitration has been investigated. The way in which the structure and conformation of the polysaccharide affected the rates of derivatization was discussed. 

Pneumococcal Sill polysaccharide has been treated with a water-soluble carbodi-imide and then reduced with sodium borohydride the i.r. spectrum of the reduced polysaccharide showed negligible absorption attributable to the presence of carboxy-groups. The reduced material furnished 1,4,5-tri-O-acetyl-2,3,6-tri-0-methyl- and 1,3,5-tri-0-acetyl-2,4,6-tri-0-methyl-D-glucitol following methylation, hydrolysis, further reduction, and acetylation, compatible with the presence of equal proportions of (1 3)- and (1 - 4)-linkages. The reduced 

Starch.—Changes induced in the physical properties and DP of starch by y-radiation have been investigated under conditions used for graft copoly-merization. The alkali-sensitive material produced on irradiation was considered to contain j3-alkoxycarbonyl functions. 

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J. F. Robyt, Mechanism in the glucansucrase synthesis of polysaccharides and oligosaccharides from sucrose, Adv. Carbohydr. Chem. Biochem., 51 (1995) 133-168. 

In addition to their important roles as stored fuels (starch, glycogen, dextran) and as structural materials (cellulose, chitin, peptidoglycans), polysaccharides and oligosaccharides are information carriers they serve as destination labels for some proteins and as mediators of specific cell-cell interactions and interactions between cells and the extracellular matrix. Specific carbohydrate-containing molecules act in cell-cell recognition and... 

Various techniques have been utilized for sequencing the glycosyl residues of polysaccharides and oligosaccharides. These techniques are elaborations of the commonplace procedure of converting polysaccharides, by partial hydrolysis, into structurally analyzable oligosaccharides. This conversion is generally achieved by partial hydrolysis with acid, by acetolysis,131 or by formolysis.62 These reagents may differ in the... 

Polysaccharides and oligosaccharides are formed from a wide variety of hexoses. 

Related topics Protein glycosylation (H5) Polysaccharides and oligosaccharides (J2)... 

MECHANISMS IN THE GLUCANSUCRASE SYNTHESIS OF POLYSACCHARIDES AND OLIGOSACCHARIDES FROM SUCROSE... 

Dirt, soils, and clays Retention of particulates and colloids in turbid water supplies concn of fines in kaolin processing Polysaccharides and oligosaccharides Concn of starch effluents concn of pectin extracts... 

Low molecular weight polysaccharides and oligosaccharides are common synthetic targets [21]. Many of them have found applications as pharmaceuticals [22,23] and nutriceuticals [24,25] (also known as fimctional foods). As specialty chemicals, these materials have been used, for example, as binders, encapsulants, protective colloids, bulking agents, and film formers. 

Polysaccharides and oligosaccharides may induce or inhibit blood coagulation depending on their structure. Chitosan and polysaccharides extracted from the Chinese laquer showed biological activity promoting the blood coagulation [173,... 

K. H. Meyer and P. Rathgeb, Starch. XLV. Terminal group analysis of polysaccharides and oligosaccharides by periodate, Helv. Chim. Acta, 32 (1949) 1102-1107. 

Each reaction mixture contained Tris-maleate, (pH 7.0), 5 ymol GDP-D-(l C) mannose, 25 nmole MnCl2, 1.5 ymol 2-mercaptoethan-ol, 0.3 ymol peptidophosphogalactomannan, 3 mg and membrane preparation, 150 yg. Incubations were carried out at 25°C for indicated interval, and the reaction stopped by heating at 100°C for 2 min. The low molecular weight substances were removed by dialysis. Each sample was treated with 0.5 M NaOH for 24 hr, neutralized and chromatographed on paper and the radioactivity in the polysaccharide and oligosaccharide peaks determined. 

Modification of Polysaccharides and Oligosaccharides, and Uses of Modified Polysaccharides and Oligosaccharides... 

Polysaccharides and oligosaccharides are widely produced in nature. Animals and plants are the most important producers in terms of volume, whereas microorganisms produce much wider diversity. Also, the small-scale structure, the proportion of different sugars and the type of linkage play an important role in the final properties of these biopolymers. Thus, applications of these poly- and oligo-saccharides are also very different, from low-to high-added value products. 

Nazarenko EL, Komandrova NA, Gorshkova RP, Tomshich SV, Zubkov VA, Kilcoyne M, Savage AV (2003) Structures of polysaccharides and oligosaccharides of srane Gram-negative marine Proteobacteria. Carbohydr Res 338 2449-2457... 

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