Amylose chemical structure

Figure 3.1 Chemical structures of the current most successfully employed derivatised polysaccharide CSPs. (a) CHIRALPAK AD Amylose tris (3,5-dimethylphenylcarbamate) coated onto a silica support, (b) CHIRALPAK AS Amylose tris [(S)-a-methylbenzylcarbamate] coated onto a silica support, (c) CHIRALCEL OD Cellulose tris (3,5-dimethylphenylcarbamate) coated onto a silica support, (d) CHIRALCEL OJ Cellulose tris (4-methylbenzoate) coated onto a silica support.

FIGURE 2 The chemical structures of (a) cellulose and (b) amylose polymers. 

FIGURE 3 The chemical structures of cellulose benzoate, amylose benzoate, and carbamate derivatives. (From Ref. 32.)... 

The triester and triphenylcarbamate derivatives of amylose were prepared as in the case of cellulose, but the triester derivatives of amylose are not useful for chiral resolution. Therefore, the triester derivatives of amylose have not been studied extensively. The chemical structures of the triphenylcarbamate derivatives are shown in Fig. 3. Similarly, the chiral resolution power of amylose derivatives was studied by introducing electron-donating and electron-withdrawing groups on the phenyl ring of the amylose derivatives [21-24],... 

The synthetic ( )-calanolide A was resolved into its enantiomers, (+)-calanolide A (1) and ( )-calanolide A, by using a semipreparative chiral HPLC column packed with amylose carbamate eluting with hexane/ethnol (95 5). The ultraviolet detection was set at a wavelength of 254 nm. (+)-calanolide A and its enantiomer (—)-calanohde A were collected, and their chemical structures were identified based on their optical rotations and spectroscopic data, as compared with the corresponding natural and synthesis compounds. 

Most starches are composed of two kinds of polysaccharides, a linear o -(1 4) linked glucan, called amylose, and an o -(1 4) linked glucan with 4.2 to 5.9% a-(l 6) branch linkages, called amylopectin. See O Fig, 1 for the chemical structure of a segment of amylose and a segment of amylopectin and O Table 1 for the percent branching in amylopectin for several different starches. 

Fig. 6.4 Chemical structures of cellulose- and amylose-based CSPs.

Fig. 7.5 Su mma7 of the chemical structures and tradenames of the most important cellulose and amylose derivatives incorporated in polysaccharide-type chiral stationary phases.

Although the essential features of the structural modifications undergone by amylose on pyrolysis are now established, full investigations of the dextrinization of the more complicated, amylopectin component have yet to be attempted. The most useful approach in this aspect of the field is to correlate the changes in such physical properties as molecular size with alterations in chemical structure. 

With the exception of cellulose and chitin, plant polysaccharides are usually hydrated. Hydration often occurs in the crystalline regions as well as in the amorphous areas. When water of hydration is found in the crystallites, it may or may not affect the conformation of the polysaccharide backbone and in most cases, it affects the unit-cell dimensions, while in a few cases, the water appears to have no effect on unit-cell dimensions. The structures of six hydrated neutral polysaccharides will be examined with regards to the state of water of hydration in the structure. It wi 11 be seen that water may occur as columns or as sheets in these structures. The structures that will be discussed are (1 4)-3-p-xylan, nigeran, amylose, galactomannan, (1 3)-3-p-gTucan and (1 3)-s-P-xy1 an. The chemical structures of these polysaccharides are shown in Figure 1. 

Figure 4.1 Chemical structures of (a) amylose, (b) amylopectin and (c) the architecture of amylopectin, according to Robin and Mercier [14],...

Figure 9.8. Simplified chemical structures of amylose a) and amylopectin b)...

Pullulan is a neutral glucan (like amylose, dextran, cellulose), with a chemical structure more or less depending on carbon source, producing microorganisms (different strains of Aureobasidium pullulans) and the fermentation conditions. ... 

Fig. 4.1 Chemical structures and physical schematic representation of a amylopectin starch, and b amylose starch...

FIGURE 28.2 Chemical structures and compositions of (a) amylose and (b) amylopectin. 

Figure 14 Chemical structure of starch, specifically, amylose and amylopectin.

A combination of the molecular polyelectrolyte theory with the methods of statistical mechanics can be used at least for the description of the chain expansion due to charges along the polysaccharide chain. The physical process of the proton dissociation of a (weak) polyacid is a good way to assess the conformational role of the poly electrolytic interactions, since it is possible of tuning poly electrolyte charge density on an otherwise constant chemical structure. An amylose chain, selectively oxidized on carbon 6 to produce a carboxylic (uronic) group, has proved to be a good example to test theoretical results. ... 

Fig. 2.34 The chemical structures of guar gum and starch components amylose and amylopectin.

Figure 4A.11 Chemical composition of amylose and amylopectin. (a) Structure of amylose (b) Structure of amylopectin. ((a) and (b), Adapted from BeMillerJN, Whistler RL. Carbohydrates. Food Chemistry. 3rd ed. New York Marcel Deker 1996. pp. 157-223)...

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