Amylose signals

A method of determining airborne iodine has also been reported.241 Here, iodine is absorbed into 5% aqueous KI and spectrophotometrically determined at 590 nm in the form of its complex with starch. This method is selective with respect to bromine and chlorine, and the sensitivity of this method is 0.25 mg of I2 per m3 of air. The concentration of the, 31I isotope in water can be determined by a method involving isotope exchange in the starch-iodine complex.242 Flow-injection determination of ascorbic acid (0.1-40 mg/mL) has been proposed.243 Iodine is generated in the flow system as I3- ions, which are in turn exposed to starch to produce a steady signal at 350 and 580 nm. Ascorbic acid provides inversed maxima which are measured. This method is recommended for analysis of ascorbic acid in fruit juice, jam, and vitamin-C preparations. Use of the blue complex has also been reported for determination of sodium dichloro-isocyanurate in air.244 Obviously the blue reaction is applicable in the determination of amylose, amylopectin, and starch,245-252 as well as modified starches.245,253-255... 

The water-soluble starch used contains 27 % amylose and 73 % amylopectin, and the oxidized starch can be isolated as a gel. The characteristic signal for the carboxylic Cg group was monitored at <5 = 176.5. Signals due to the corresponding aldehyde groups were not seen (Structure 4). 

It was shown that amylose gel contains two kinds of C NMR signals the B-type signals from motionally restricted regions as recorded by the CP-MAS NMR technique and the signals identical to those found in aqueous solution [43]. The latter signals could be ascribed to flexible molecular chains adopting... 

This observation is very similar to the downfield displacements of C-1 and C-4 carbons (in the glucosidic linkages) of cyclodextrins (1.6-2.0 and 2.9 ppm, respectively) compared with those of the linear (l-wl)-a-D-glucans such as amylose (30). In the formers,it appears that no overall internal rotation around the C-1-0 and C-4-0 linkages is allowed because of its cyclic structure. In a similar manner, the C-1 and C-3 signals, which exhibit the conformation-dependent downfield displacements observed in the gel state, can be ascribed to certain ordered conformations in which only a slight oscillation around the favored dihedral angle around the... 

With all iodine solutions (without amylose) containing 1 (b-d) a main signal is observed at 111 cm l. Based on the vibrational analysis of the 13 ion by Maki and Forneris (27), this signal was assigned by Tasumi (28) to the symmetric stretching vibration of 13 . With the... 

The resonance Raman spectra of solutions of iodine-complexed amyloses with DP 18, 47 and 190 are shown in Figure 4. Most strikingly, the resonance Raman spectra are almost identical inspite of the considerably different absorption spectra of these samples. A main band at 162 cm l, typical of complexed iodine ( 5,, , ), and a band at 111 cm l are observed. Heyde et al. (30) found two additional bands at 27 and 57 cm the former can be seen in the spectra of DP 47 and 190 in Figure 4. The 57 cm band is superposed by a group of signals located between 80 and 35 cm , which turned out to be due to instrumental artifacts. Overtones and combination vibrations were found at 185, 217, 272 and 322 cm-1. 

The spectra do not show time dependent changes. In the range of the sugar vibrations, 500-1500 cm , resonance enhanced signals, which would have indicated strong interactions between iodine and amylose, were not observed. 

Resonance Raman measurements with iodine-complexed amyloses have shown that the vibration modes typical of the iodine species bound in the complex do not depend on the length of the polyiodine chain. Evidently these signals only give information about short sections of the polyiodine chain, as could be expected on the basis of Raman spectroscopy. Even at... 

To understand better the nature of the observed ESR signals additional experiments were performed. Amylose powder ground in an agate mortar. 

From the chemical shifts of the 13-C and 1-H signals, it is concluded that a phlorizin molecule enters into the hydrophobic space of 3-CD or Y CD and makes a loose molecular complex with 3-CD or yCD. The fact that the H-D exchange reaction in phlorizin is suppressed by 3-CD or y-CD supports the above conclusion. On the other hand, it is found that a phlorizin molecule does not enter into the inner space of a-CD and interacts with a-CD locally as in the case of amylose. 

C NMR spectra were obtained with a JEOL FX 200 spectrometer and 1-H NMR spectra were obtained with a JEOL GX 400 spectrometer. An aqueous solution of Phz (1.5-3.0 10" mol/1) was used as a sample for NMR spectra. External TMS was used as a reference for 13-C signals, while in the measurement of 1-H NMR signals, sodium trimethylsilylpropionate-d was used as an internal reference. Phz(Sigma Chemical Company), CDs(Nakarai Chemicals LTD) and amylose(Hayashibara Biochemical Laboratories Inc.) were used without any purification. 

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