The conformational behavior of amylose and the formation of helical inclusion complexesof amylose with a substrate, N-ethyl-4-hexadecyloxycarbonyl pyridinium iodide (1) -- asolvent-polarity probe, have been investigated in the DMSO--H_2O mixed-solvent system bymeans of surface tension, viscosity, UV, electrical conductance and ORD measurements. Thedecrease of the volume-fraction of DMSO, Φ_(DMSO) of the mixed-solvent system inducesconformational changes of the amylose from tight helices to loose and extended helicesinterrupted by short disordered regions. Such a transition is accompanied by abrupt changesof the viscosity and ORD curves. The mechanism of interaction between amylose and the substrate 1 also depends on thesolvent composition. When Φ_(DMSO) is larger than 0.70, the interaction of amylose with 1is apparently similar to those cases in which superhelices are formed between a macromo-lecule and some azo dyes; the latter are known to be bound exteriorly around the macro-molecular helices by oriented association. However, when Φ_(DMSO) begins to drop below0.70, the substrate molecules start to be bound in the helical cavities of the host and thussupramolecular inclusion complexes are formed. At Φ_(DMSO)<0.70, ORD shows a new nega-tive Cotton peak at a wavelength which coincides with the λ_(max) of 1 (276 nm). This implicatesinduced asymmetry for the achiral substrate 1 in a chiral microenvironment. Intrinsicdissociation constants (K_(d~*)) for the inclusion complexes can be obtained from the surface ten-sion- substrate concentration (σ-[1]) curves and the largest number of binding sites isfound to be below 30. The K_(d~*) values decrease with decreasing Φ_(DMSO), apparently inagreement with the results from conductance measurements. Presumably, the driving forcefor the transfer of the substrate molecules from the solvent-mixture bulk phase to the non-polar cavities of the host molecules comes from hydrophobic-lipophilic interactions. The conformational behavior of amylose and the formation of helical inclusion complexes of amylose with a substrate, N-ethyl-4-hexadecyloxycarbonyl pyridinium iodide (1) -asolvent-polarity probe, have been investigated in the DMSO-H 2 O mixed-solvent system bymeans of surface tension, viscosity, UV, electrical conductance and ORD measurements. The volume of the volume-fraction of DMSO, Φ_ (DMSO) of the mixed-solvent system induces formation of of the amylose from tight helices to loose and extended helicesinterrupted by short disordered regions The mechanism of interaction between amylose and the substrate 1 also depends on the solvent composition. When Φ_ (DMSO) is larger than 0.70, the interaction of amylose with 1is apparently similar to those cases in which superhelices are formed between a macromo-lecule and some azo dyes; the latter are known to be bound around exteriorly around the macro-molec However, when φ_ (DMSO) begins to drop below 0.70, the substrate molecules start to be bound in the helical cavities of the host and thussupramolecular inclusion complexes are formed. At Φ_ (DMSO) <0.70, ORD shows a new nega-tive Cotton peak at a wavelength which coincides with the λ max (1) at 276 nm. This implicates induced asymmetry for the achiral substrate 1 in a chiral microenvironment. Intrinsicdissociation constants (K_ (d ~ *)) for The inclusion complexes can be obtained from the surface ten-sion-substrate concentration (σ- [1]) curves and the largest number of binding sites is found to be below 30. K_ (d ~ *) values ​​decrease with decreasing Φ_ (DMSO ), apparently in effect with the results from conductance measurements. Presumably, the driving force for the transfer of the substrate molecules from the solvent-mixture bulk phase to the non-polar cavities of the host molecules comes from hydrophobic-lipophilic interactions.