FLUORESCENCE STUDY OF THE STATE OF TRYPTOPHANE IN AQUEOUS DIMETHYLSULFOXIDE

The fluorescence spectra of tryptophane were measured in a wide range of concentrations of aqueous dimethylsulfoxide (DMSO) solutions. In so lutions with different compositions, tryptophane is surrounded by wate r molecules alone. This result is in agreement with the known fact of microseparation of aqueous DMSO solutions. Evidently, in a water-DMSO system, the tryptophane molecules are built into water microregions, i n which they have a pure aqueous environment and are thus isolated fro m the nonelectrolyte present in the solution. Based on the experimenta l data tee determined induced relaxation time of water molecules formi ng the nearest environment of excited tryptophane (0.59 ns for aqueous tryptophane).