Amylose iodine complex

Rundle and coworkers166 found that the wave length of maximum absorption (Amflx) of the amylose-iodine complex is related to the chain length... 

Observed Relationship Between Xmax and D. P. for Amylose-Iodine Complexes... 

The amylose-iodine complex is shown here. Amylase, an enzyme in your saliva, broke down the amylose in the solution you spit into, meaning there is less starch present to react with the iodine and consequently a lighter blue solution. 

The mature kernel phenotype for the triple mutant ae du su is similar to that for su (Table 3.3). Sugar concentrations of mature272 and immature270 ae du su kernels are higher than those of either of the single mutants or the double mutants ae du or ae su, while starch concentration is similar to that in su and the two double mutants. The amylose percentage is close to that of normal when measured by either the blue value test (Table 3.6) or SEC (Table 3.7). However, in contrast to normal, a major proportion of the branched polysaccharide is smaller than typical amylopectin (as is that of ae su), and it elutes from an SEC column at an intermediate position (Table 3.7). The absorbance maximum and absorptivity (extinction coefficient) of the branched polysaccharide-iodine complexes are similar to those for ae and ae su, and are characteristic of loosely-branched polymers. The absorbance maximum of the amylose-iodine complex is similar to that of normal, du, or su, but the absorptivity is lower than for either (Table 3.7). No short chain amylose has been found in ae du su starch.90... 

Amylose-iodine complexes have a deep blue color, which is a result of an electron relay on the polyiodide ions.196 The helix of amylose provides a tunnel for iodine molecules to align. Stability of the amylose-iodine complex has been studied.197 Iodine has been widely used for quantification of amylose contents despite the fact that the blue color development is affected by many factors, including temperature, pH and mechanical mixing. Several improved methods have been reported (see Section 6.III.1). 

Eight combinations (types 1-8, Table 10.12) of Wx-Al, Wx-Bl and Wx-Dl proteins are possible in common wheats.257 Near-isogenic lines of the eight types of wheats showed apparent amylose levels of 3% to 25%, as determined by the blue color of the amylose-iodine complex.266 The amylose level in wheat kernels increases positively with the level of waxy proteins.257,269 271 In the double nulls, the Wx-Al protein in type 5 wheat produces —3% less amylose than the Wx-Bl and Wx-Dl proteins (types 6 and 7, respectively). In the single nulls, compared to the wild type (type 1), absence of Wx-Bl (type 3) reduces the amylose content by —2% compared to —1% for the absence of either of the other two waxy proteins (types 2... 

Starch can form an intense, brilliant, dark blue-, or violet-colored complex with iodine. The straight chain component of starch, the amylose, gives a blue color while the branched component, the amylopectin, yields a purple color. In the presence of iodine, the amylose forms helixes inside of which the iodine molecules assemble as long polyiodide chains. The helix-forming branches of amylopectin are much shorter than those of amylose. Therefore, the polyiodide chains are also much shorter in the amylopectin-iodine complex than in the amylose-iodine complex. The result is a different color (purple). When starch is hydrolyzed and broken down to small carbohydrate units, the iodine will not give a dark blue (or purple) color. The iodine test is used in this experiment to indicate the completion of the hydrolysis. 

OD660 for Amylose/ Iodine complex OD530 for Amylopectin/ Iodine complex... 

Noltemeyer M, Saenger W (1980) Structural chemistry of linear a-cyclodextrin-polyiodide complexes. X-ray crystal structures of (a-cyclodextrin)2 Lil3 I2 8 H20 and (a-cyclodex-trin Cdoj Ij 27 0. Models for the blue amylose-iodine complex. J Am Chem Soc 102 2710-2722... 

Fig. 4.—Effects of various salts on the formation of the amylose-iodine complex. The effect is expressed as the shift of the 605-nm band (above) and the variation of the extinction of that band (below). 1, KC1 2, NaN03 3, (NH4)2S04 4. CaCl2 5, ZnS04 6, KBr 7, KI. (From Kuge and Ono.91)...

Fig. 5.—Changes of absorbance of the amylose-iodine complex (at 610 nm with increasing concentrations of various salts) 1, A12(S04)3 2, Pb(N03)2 3, Na2S04 4, NH4C1 5, CH3C02Na 6, Sr(N03)2 7, KI 8, KN03. (From Kuge and Ono.91)...

Fiu. 7.—Space pattern of one period of the amylose-iodine complex. (Reprinted with permission from J. Hollo and J. Szejtli, Period. Polytech., 2 (1958) 25-37.)... 

Studies carried out in solution provide strong evidence that the helical amylose-iodine complex also exists in such circumstances.11014 1141 The structure of the iodine-amylose complex has also received theoretical treatment,142 and a three-dimensional free-electron model was developed for quantum mechanical calculations. Ultraviolet and visible spectra simulated in this manner reached close agreement with experiment observations. 

The pathway for the formation of the amylose-iodine complex is well recognized, at least when aqueous solutions of KI and iodine are used. Relevant studies are lacking on the formation of the complexes between iodine vapor and both amylose and amylopectin. 

Fig. 14.—Variation of the absorbance at 600 nm of the amylose-iodine complex as the function of temperature. Crosses measurements on heating circles measurements on cooling. (Reprinted with permission from Nature, 197, pp. 898-899, copyright 1963 Macmillan Magazines Limited.)...

Fig. 18.—Infrared absorption spectrum of the amylose-iodine complex. [From Greenwood and Rosotti.206 Copyright 1958 John Wiley Sons. Reprinted by permission of John Wiley Sons, Inc.]...

Results of X-Ray Powder Diffraction of the Amylose-Iodine Complex"... 

Free iodine reacts with starch solution to give the blue-black amylose-iodine complex, which contains iodine in the form of an Ij" chain. The aiiiylopecliii also present in starch reacts with iodine to give a brown violet color. In concen Hated aqueous alkaline iodide solutions and in alcoholic solution iodine has an intense brown color at high dilutions this color changes to yellow because of... 

Thus the blue inclusion complex becomes visible only when all the hydrogen sulfite has been consumed. According to studies by / . C. Teitelbaum, S. L. Ruby and T. ]. Marks the blue inclusion compound consists of the amylose component of the starch and the polyhalogenide anion Is", this was established by comparing the Raman and I Mofibauer spectra of the blue-black amylose-iodine complex with those of the adduct between trimesic acid hydrate and H Is , the structure of which is known (see figures). 

When starch is fractionated into its two components, usually by precipitating the amylose from solution by means of an organic solvent (such as an alcohol), a third type of structure is found this survives drying, and ultimately reverts to the B structure upon rehydration. This structure has been termed the V form, and it yields an x-ray pattern that is distinctly different from the other two types. Essentially the same pattern was observed for the amylose-iodine complex. Bundle and coworkers studied the various V amyloses obtained by complexing with alcohols or iodine, and, on the basis of powder diagrams, suggested unit-cell parameters for both the wet and dry (hydrated and anhydrous) states, as shown in Table I (seep. 422). From these data, Bear had suggested earlier that the "V structure of amylose is helical. (Historically, it is of... 

Two methods were used one is the iodine method that was used to determine dextrinization or the ratio of hydrolysis of the starch, and the other is the phenolphifaalein method lhat was used to determine CD formation. Starch-dextrinizing activity was determined in accordance with Fuwa (19) and Pongasawasdi and Yagisawa (20) with slight modifications. The reaction mixture containing 100 (iL of diluted enzyme aliquot and 300 pL of 0.5% soluble starch prepared in 0.1 M acetate buffer, pH 5.5, was incubated at 55 °C for 10 min. The enzyme reaction was stopped by the addition of 4.0 mL of 0.2 M HCl solution. Then, 0.5 mL of iodine solution (0.3 g/L I2 and 3.0 g/L KI) was added to form an amylose-iodine complex with residual amylose. The final volume was adjusted to 10 mL with distilled water. The absorbance of the blue color of the amylose-iodine complex was measured by spectrophotometer at 700 nm, and a decrease in absorbance was verified, when compared to a control tube with heat-inactivated enzyme. One unit of enzyme activity was defined as the quantity of enzyme that reduces the blue color of the starch-iodine complex by 10% per minute. 

The extinction coefficient of the amylose-iodine-complex, the wavelength of the maximum absorption and the stability is Influenced by the degree of polymerization of the amylose chain (i2 22). Formation of "che amylose-iodlne-complex is affected by temperature, pH, ionic strength, concentration of iodide ions and the nature of amylose. 

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