Amylose molecular weight

The phosphate groups in starch are found mostly in the amylopectin portion. A mobile phase without salt may be suitable for the determination of amylose molecular weight or amylose percentage in a sample, but it should be used with caution. 

Cellulose is a high molecular weight polymer of D-glucose with fi( 1 -4)-glycosidic bonds, found in plant fibres it is the major component of most plant tissues. Starch is another common polysaccharide, containing two polymers of glucose, amylose and amylopectin. It was used in some paint preparations and in the production of paper. Acid treatment of starch produces dextrins, which are used as adhesives and additives in water colour paintings. 

Addition of an aqueous solution of PEG to a saturated aqueous solution of a-CD at room temperature did not lead to complex formation unless the average molecular weight of PEG exceeded 200 [46]. Moreover, carbohydrate polymers such as dextran and pullulan failed to precipitate complexes with PEG, and the same was true for amylose, glucose, methyl glucose, maltose, maltotriose, cyclodextrin derivatives, such as glucosyl-a-CD and maltosyl-a-CD, and water-soluble polymers of a-CD crosslinked by epichlorohydrin. These facts suggested to Harada et al. the direction for further research. 

The labile nature of the components necessitates that, for fundamental investigations, the starch should preferably be extracted from its botanical source, in the laboratory, under the mildest possible conditions.26 Industrial samples of unknown origin and treatment should not be used. The characterization of the starch would appear to entail (1) dissolution of the granule without degradation, (2) fractionation without degradation, (3) complete analysis of the finer details of structure of the separated components (including the possibilities of intermediate structures between the extremes of amylose and amylopectin), and (4) the estimation of the size, shape, and molecular-weight distribution of these fractions. 

Comparison of Chemical End-group Assay and Corresponding Molecular-Weight Determinations for Amylose... 

Several investigations of the molecular weight of subfractions of amyloses... 

The Results of Molecular-Weight Determinations on Acetylated Amyloses... 

These synthetic linear and branched molecules may be important as type polymers, particularly if the interconversion of amylose to amylopectin is intramolecular, in which case the initial molecular weight and molecular-weight distribution would be retained. There is the possibility that the in vitro synthesis may even result in a truly three-dimensional structure, as distinct from that of the natural component. 

Amylose has a lower molecular weight than amylopectin but forms linear chains while amylopectin has a higher molecular weight but forms more compact molecules. While both molecules have a structure mainly based on a-(l - 4)-D-glucose units, the amylopectin structure is branched at the a-(l - 6)-D-glucose units. 

Amylose. Amylose molecules are composed of single chains, mainly but not exclusively unbranched, consisting of 500-200 000 a-(1 - 4)-D-glucose units. The molecular weight depends on the plant from which the amylose has come. Although a small quantity of a-(l -> 6)... 

Fraction 1 (number) Yield in percent of amylose Reducing value as percent glucose Average molecular weights Average degrees of polymerization... 

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