Amylose soluble

In these plant organs, starch is present in the form of microscopically small granules in special organelles known as amyloplasts. Starch granules are virtually insoluble in cold water, but swell dramatically when the water is heated. Some 15-25% of the starch goes into solution in colloidal form when the mixture is subjected to prolonged boiling. This proportion is called amylose ( soluble starch ). 

Amylose (soluble starch) Natural, linear component of starch c 0 c C OH Substituted pyranose sequences... 

Starch consists of two chemically distinct polysaccharide fractions, amylose (soluble in hot water) and amylopectin (insoluble in hot water). Amylose is a linear polymer of a-... 

Conditions for the maximum yield of extracellular a-amylase from Bac-teroides amylophilus have been reported. Isoelectric focusing and polyacrylamide gel electrophoresis demonstrated the presence of six isoenzymes one of these was purified by ion-exchange chromatography and gel filtration. This enzyme (pH optimum 6.3, temperature optimum 43 °C, pH stability range 5.8—7.5, p7 4.6, mol. wt. 9.2 x 10 by sodium dodecyl sulphate-polyacrylamide gel electrophoresis) was inhibited by cyclo-hexa and hepta-amyloses, phenyl a-D-glucopyranoside, and Hg + whereas Ca + and Co were strong activators. The relative rates of hydrolysis of amylose, soluble starch, amylo-pectin, and dextrin were 100, 97, 92, and 60%, respectively (Am values 18.2, 18.7, 18.2, and 16.7 [xmol D-glucosidic bonds 1, respectively). 

Starch can be split into amylose and amylopectin by a commercial process based on selective solubilities. Amylose is used for making edible films, and amylopectin for textile sizing and finishing, and as a thickener in foods. 

As a thickener (as opposed to a gel), it is amylose that has the main function. The long water-soluble chains increase the viscosity, which doesn t change much with temperature. Amylose chains tend to curl up into helixes (spirals) with the hydrophobic parts inside. This allows them to trap oils, fats, and aroma molecules inside the helix. 

Figure 17-5. Amylose, cellulose. Amylose consists of a water-soluble portion, a linear polymer of glucose, the amylose and a water-insoluble portion, the amylopectin. The difference between amylose and cellulose is the way in which the glucose units are linked. In amylose, a-linkages are present, whereas in cellulose, p-linkages are present. Because of this difference, amylose is soluble in water and cellulose is not. Chemical modification allows cellulose to become water soluble.

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. 

These water-soluble molecules are cyclic oligomers of a-D-glucose formed by the action of certain bacterial amylases on starches (Bender and Komiyama, 1978 Saenger, 1980 Szejtli, 1982). a-Cyclodextrin (cyclohexa-amylose) has six glucose units joined a(l, 4) in a torus [1], whereas /3-cyclodextrin (cycloheptaamylose) and y-cyclodextrin (cyclooctaamylose) have seven and eight units, respectively. 

Soluble Starch comprises principally of f3-amylose, with the a-fraction having been removed. Always, it is a practice to prepare indicator-solutions from this product exclusively. 

Table I lists physical data for a number of the carbamate and ester derivatives of cellulose, chitin, amylose, amylopectin, and dextran synthesized as described in the Experimental Section. The solubility of the polysaccharide starting materials as well as that of the produced derivatives allows for macromolecular characterization through techniques including UV, NMR, IR, high pressure liquid chromatography, etc.

High temperatures can break native S-S bonds and form new S-S bonds which can lock the protein into a denatured eonfiguration [89]. Low pH, sodium dodecyl sulfate. Tween 80, chaotropie salts, and exogenous proteins have been used to protect proteins from thermal inaetivation [90]. Ethylene glycol at 30-50% was used to protect the antiviral activity of P-interferon preparations [91]. Human serum albumin was used in recombinant human interferon-Psei-n which resulted in increased thermal stability [62]. Water-soluble polysaeeharides sueh as dextrans and amylose [92], as well as point-specific (site-directed) mutagenesis [93] have also been used to increase thermal stability of therapeutie proteins and peptides. 

Solutions of 1% (w/v) puUulan, amylose, amylopectin, mammalian glycogen, oyster glycogen and soluble starch (pH 6.0) were incubated at 60 C with purified enzyme (0.05 U/ml). Samples were withdrawn after 216 hrs and heated at lOO C for 15 min for enzyme inactivation. The reaction products were analyzed by HPLC for sugars. (12). (Reprinted with permissicm from Ref. 13. Copyright 1990 Academic Press, Inc.)... 

Figure 3. Kinetics of conq)etitivc inhibition of Clostridium thermohydrosuljur-icum strain 39E purified amylopuUulanase activity with mixed substrates. The solid lines A and C indicate the theoretical plots for competitive inhibition at amylose ccmcentrations of 0.6 and 2.4 mg/ml, respectively. Lines B and D are the theoretical plots for the absence of inhibition at the same respective amylose ccmcentrations. PuUulan was used at concentrations of 0.4, 0.8, 1.2, 1.6, 2.0, 2.4 mg/ml. For clarity, only two sets of data points were used in the above plot. ( ) and (A) are the practical data points obtained at 0.6 and 2.4 mg/ml amylose concentrations. All reaction mixtures contained 5% (v/v) dimethyl sulfoxide for solubility of amylose. [S] = [A] + [P], where S is the total substrate ccmcentration. A and P are the concentrations of amylose and pullulan, respectively. (Reproduced with permissiem from Ref. 13. Copyright 1990 Academic Press, Inc.)...

Amylose consists of unbranched al 4-linked chains of 200-300 glucose residues. Due the a configuration at C-1, these chains form a helix with 6-8 residues per turn (1). The blue coloring that soluble starch takes on when iodine is added (the iodine-starch reaction ) is caused by the presence of these helices—the iodine atoms form chains inside the amylose helix, and in this largely non-aqueous environment take on a deep blue color. Highly branched polysaccharides turn brown or reddishbrown in the presence of iodine. 

Amylopectin Amylopectin is similar to amylose except that the glucose chain has branches. These branches involve linkages at the -CH2OH position ( 6), which makes them a 1 —> 6 linkages. Amylopectin is water-soluble it also interacts with iodine to form a reddish-purple complex. Typically, amylopectin is ten times the size of an amylose molecule. Digestion requires (3-amylase (1 4 linkages) and a second... 

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