TNS-amylose complex

ABSTRACT. The interaction of 2-p-toluidinylnaphthalene-6-sulfonate (TNS) with amylose and its related compounds in aqueous solution has been studied by both steady-state and transient fluorescence measurements. The fluorescence of TNS aqueous solution was enhanced by the addition of amylose, 3-limit dextrin, and amylopectin. The fluorescence decay of TNS bound to these polysaccharides were well described as a sum of two-exponential functions. This suggests that there are two different microenvironments at the binding sites. The fluorescence lifetime of major component for TNS-amylose system agreed with that of major component for TNS-y-cyclodextrin system. The mean rotational relaxation time of TNS bound to amylose is similar to that of the segmental motion of amylose chain. Based on these results, a configurational model for TNS-amylose complex has been proposed. 

TABLE II. Effect of temperature on the fluorescence lifetime of TNS-amylose complex... 

Figure 1 shows the fluorescence emission spectra of TNS aqueous solutions with amylose, 3-limit dextrin, and amylopectin. The figure also includes the spectrum of TNS aqueous solution without these polysaccharides. The addition of these polysaccharides to TNS aqueous solution markedly enhances the fluorescence of TNS and sifts its maximum wavelength from 00 to 60 nm, suggesting the formation of TNS-polysaccharide complex es. 

Figure 4 shows the dependences of the fluorescence intensity and polarization for TNS-amylose system on the concentration of TNS. It is seen, in contrast to the fluorescence intensity, that the fluorescence polarization of the solution is constant over the range of TNS concentration examined. This fact suggests that the molecular chain of aunylose does not undergo any great conformational change by the formation of complex with TNS. 

It has been shown that amylose forms inclusion complexes with iodine and many kinds of organic compounds in aqueous solution. Thus, the most probable model for the interaction of aunylose with TNS is an inclusion complex. Since cyclodextrins form inclusion complexes with TNS and enhance TNS fluorescence in aqueous solution ( ), it is interesting to compare fluorescence decay parameters for TNS-atmylose system with those for TNS-cyclodextrin systems. The values of lifetimes for amylose are the same as those for Y-cyclodextrin. However, the relative content of the long lifetime for amylose is much smaller than that for Y-cyclodextrin.Y -Cyclodextrin is expected to form both 1 1... 

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