Polysaccharides linkages

C9. Chakrapani, B., and Bachhawat, B. K., Glycosaminoglycans of human urine. I. Protein-polysaccharide linkage region in the non- phated glycosaminoglycans of normal urine. Indian. J. Biochem. 5, 9-12 (1968). 

Keratan sulphates I and II have been isolated and purified from bovine cornea and nasal cartilage, respectively. Desulphation of keratan sulphate I yielded both water-soluble and water-insoluble products, but keratan sulphate II yielded only water-soluble products. The water-soluble form contains glycopeptides from the protein-polysaccharide linkage region, and oligosaccharides derived from the main chain of the glycosaminoglycan associate forming water-insoluble species. 

In solution, polysaccharide linkages between the individual monomers take conformations and energies according to the Boltzmann distribution. The nomenclature of the resulting random coils is that of classical polymer theory, with the major descriptor of the shape being the characteristic ratio, Coo- The ratio is proportional to the mean square end-to-end distance, normalized for the length of the individual monomeric residues. In the solid state, the polysaccharides often form crystallites that are too small to provide sufficient diffraction information for a full determination of their structure. However, they often yield fiber diffraction patterns that give useful clues to the correct structure. 

Cation (Section 1 2) Positively charged ion Cellobiose (Section 25 14) A disacchande in which two glu cose units are joined by a 3(1 4) linkage Cellobiose is oh tamed by the hydrolysis of cellulose Cellulose (Section 25 15) A polysaccharide in which thou sands of glucose units are joined by 3(1 4) linkages Center of symmetry (Section 7 3) A point in the center of a structure located so that a line drawn from it to any element of the structure when extended an equal distance in the op posite direction encounters an identical element Benzene for example has a center of symmetry Cham reaction (Section 4 17) Reaction mechanism m which a sequence of individual steps repeats itself many times usu ally because a reactive intermediate consumed m one step is regenerated m a subsequent step The halogenation of alkanes is a chain reaction proceeding via free radical intermediates... 

Metabolic Functions. Manganese is essential for normal body stmcture, reproduction, normal functioning of the central nervous system, and activation of numerous enzymes (126). Synthesis of the mucopolysaccharide chondroitin sulfate involves a series of reactions where manganese is required in at least five steps (127). These reactions are responsible for formation of polysaccharides and linkage between the polysaccharide and proteins that form... 

The distinctions between these homopolymers arise from the different ways in which the monomer units are hooked together in polyacetal chains. Starch (qv), plant nutrient material, is composed of two polysaccharides a-amylose and amylopectin. cx-Amylose is linear because of exclusive a (1 — 4) linkages, whereas amylopectin is branched because of the presence of a (1 — 6) as well as a (1 — 4) links. The terms linear and branched refer only to primary stmcture. 

Fig. 1. Primary stmctures of some common polysaccharides, (a) Alpha-glycoside linkages characterize amylose, amylopectin, and glycogen (b) cellulose has...

Plant stmctural material is the polysaccharide cellulose, which is a linear P (1 — 4) linked polymer. Some stmctural polysaccharides iacorporate nitrogen iato thek molecular stmcture an example is chitin, the material which comprises the hard exoskeletons of kisects and cmstaceans. Chitki is a cellulose derivative whereki the OH at C-2 is replaced by an acetylated amino group (—NHCOCH ). Microbial polysaccharides, of which the capsular or extracellular (exopolysaccharides) are probably the most important class, show more diversity both ki monomer units and the nature of thek linkages. 

Sections Disaccharides are carbohydrates in which two monosaccharides are 25.14-25.15 joined by a glycoside bond. Polysaccharides have many monosaccharide units connected through glycosidic linkages. Complete hydrolysis of disaccharides and polysaccharides cleaves the glycoside bonds, yielding the free monosaccharide components. 

Amylopectin (Section 25.15) A polysaccharide present in starch. Amylopectin is a polymer of a(l,4)-linked glucose units, as is amylose (see aniylose). Unlike amylose, amylopectin contains branches of 24-30 glucose units connected to the main chain by an a(l,6) linkage. 

Cellulose (Section 25.15) A polysaccharide in which thousands of glucose units are joined by (3(1,4) linkages. 

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