Polysaccharides amylose type

Extracts of Neisseria perflava contain phosphorylase also, but this could be differentiated from amylosucrase, which is specific for sucrose and has no action on a-D-glucosyl phosphate. The polysaccharide has been investigated by methylation and enzymic analysis, and the presence of branched chains of (1— 4)-linked a-D-glucose residues rigidly established. The acceptor specificity of amylosucrase has not been studied in detail, but maltosaccharides and small amylose-type molecules are logical acceptors, especially as amylosucrase action on sucrose is inhibited by a-amylase. 

Starch is a polysaccharide composed exclusively of D-glucose and is one of the three most abundant organic compounds found on Earth (cellulose and murein being the other two abundant compounds). Most starches are composed of two types of polysaccharides amylose and amylopectin. The former is a mixture of linear polysaccharides of D-glucose units linked a-1 4 to each other. The latter consists of a mixture of branched polysaccharides of D-glucose unit linked a-1 4, with 5% of a-1 6 branch linkages corre-... 

Rice is one of the world s primary food crops and is a major source of dietary energy for more than half of the people on this planet. Paddy is usually milled or polished into white rice for cooking even though unpolished rice contains much more nutritional bioactive components and dietary energy. A major component of rice grain is starch, which in turn is composed of polysaccharides two types of polysaccharides found in rice starch are amylose and amylopectin. The amounts of amylose and amylopectin determine the quality of rice, both in terms of physical and chemical characteristics. 

Phosphorylases, which occur in a wide variety of sources, converts D-glu-cose 1-phosphate into an amylose type of polysaccharide with the formation of inorganic phosphate 166), The over-all reaction may be expressed as ... 

Amylosucrase 173) from Neisseria perflava utilizes sucrose for the synthesis of polysaccharides with properties intermediate between those of glycogen and amylopectin 174). Apparently, there are two enzymes responsible for this synthesis one enzyme converts sucrose into an amylose-type polysaccharide and the other enzyme, which is of the Q-enzyme type, breaks the straight chains to produce highly branched molecules. The resultant branched polysaccharides have about 12 D-glucose units for each nonreducing end unit. 

A polysaccharide is a polymer of many monosaccharides joined together. Four biologically important polysaccharides—amylose, amylopectin, glycogen, and cellulose— are all polymers of o-glucose that differ only in the type of glycosidic bonds and the amount of branching in the molecule. 

Storage polysaccharides of Prochloron isolated from Lis-soclinum pateUa are similar to the varieties of starch fotmd in the algae and terrestrial plants that is, the simultaneous presence of a nonramified and relatively short polymer of amylose type and a longer and strongly ramified polymer of amylopectin type (Fredrick, 1980). 

Examples with other Pirkle-type CSPs have also been described [139, 140]. In relation to polysaccharides coated onto silica gel, they have shown long-term stability in this operation mode [141, 142], and thus are also potentially good chiral selectors for preparative SFC [21]. In that context, the separation of racemic gliben-clamide analogues (7, Fig. 1-3) on cellulose- and amylose-derived CSPs was described [143]. 

Molecular Structure. Most starches consist of a mixture of two polysaccharide types amylose, an essentially linear polymer, and amylopectin, a highly branched polymer. The relative amounts of these starch fractions in a particular starch are a major factor in determining the properties of that starch. 

Starch granules are composed of two types of a-glucan, amylose and amylopectin, which represent approximately 98-99% of the dry weight. The ratio of the two polysaccharides varies according to the botanical origin of the starch. 

Most potato starches are composed of a mixture of two polysaccharides, a linear fraction, amylose, and a highly branched fraction, amylopectin. The content of amylose is between 15 and 25% for most starches. The ratio of amylose to amylopectin varies from one starch to another. The two polysaccharides are homoglucans with only two types of chain linkage, a-(l 4) in the main chain and a-(l 6)-linked branch chains. Physicochemical properties of potato and its starch are believed to be influenced by amylose and amylopectin content, molecular weight, and molecular weight distribution, chain length and its distribution, and phosphorus content (Jane and Chen, 1992). 

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