Study of polysaccharides by the fluorescence method. V. Interaction of 2-p-toluidinylnaphthalene-6-sulfonate with amylose and its related compounds in aqueous solution

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, -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--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.