Biopolymers and cell. 1988. Volume 4. № 4. 211 - 217

A. P. Demchenko, A. S. Ladokhin

RED-EDGE FLUORESCENCE SPECTROSCOPY OF INDOLE AND TRYPTOPHAN

Summary

    Studies on the dependence of indole and tryptophan fluorescence spectra on excitation wavelength Xex demonstrate the existence of the effect of the longwave fluorescence shift at the red edge-excitation in different solid and viscous solvents. In solid systems spectral shifts in the excitation range 290-310 nm reach tens of nm, and they are more significant than changes of Xex. In the viscous medium the magnitude of this effect is directly related to the dipole-reorientational relaxation of solvent molecules in the chromophore environment, which allows the relaxation times to be estimated. The method involves simple steady-state experiments of fluorescence spectra at the maximum and at the red edge of absorption band. It may be advantageous when studying proteins, since there is no necessity to obtain information on the fluorescence spectra of completely relaxed states.