Amylopectin iodine interaction

Molecular Interactions. Various polysaccharides readily associate with other substances, including bile acids and cholesterol, proteins, small organic molecules, inorganic salts, and ions. Anionic polysaccharides form salts and chelate complexes with cations some neutral polysaccharides form complexes with inorganic salts and some interactions are stmcture specific. Starch amylose and the linear branches of amylopectin form inclusion complexes with several classes of polar molecules, including fatty acids, glycerides, alcohols, esters, ketones, and iodine/iodide. The absorbed molecule occupies the cavity of the amylose helix, which has the capacity to expand somewhat to accommodate larger molecules. The starch—Hpid complex is important in food systems. Whether similar inclusion complexes can form with any of the dietary fiber components is not known. 

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... 

Glycogen, animal starch, is similar to amylopectin, but it features more branching and tends to have a higher molecular weight. Glycogen occurs in the liver and muscle tissue. It interacts with iodine to produce a red color. 

The Interaction of Sodium Dodecyl Sulfate, a Competing Ligand, with Iodine Complexes of Amylose and Amylopectin... 

Amylose and amylopectin are the Isotactlc homo-polymers of oc-D-glucose which interact with iodine (13) in aqueous systems to give the characteristic blue coloured complexes. 

The competing ligand like SDS, appears to interact with the loose helical regions in amylose and amylo-pectin to form the corresponding compact helical complexes with SDS molecules trapped Inside the helices, when lodine(I3) is added to this system, a part of the SDS, which is loosely attached is displaced by iodine(I ). The absorption spectra of the resulting amylose-SDS-iodine-ccmplex/amylopectin-SDS-iodine-complex, when compared with their respective spectra in absence of SDS, show a reduction in... 

Amylose is a unique polysaccharide which forms a helical blue-coloured complex with iodine (I5). It also forms helical complexes with a variety of organic compounds such as 1-butanol, 1-pentanol, cyclohexanol, SDS etc. The interaction of SDS, a competing ligand with iodine (I ) complexes of amylose and amylopectin is studied spectrophotometrically. It is observed that the reduction in absorbance at 640 nm accompanied by the blue shift (640-570 nm) in the absorption spectrum is governed by the sequence of addition of the reagents, implying that this Interaction is closely associated with the coil—>hellx transition of the polymer chain. Perturbation of this complex with sodium thiosulphate and urea has revealed that the transition from helix—>coil is rather sluggish and hydrophobic interactions play an important role in the stability of this complex. 

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