Fast relaxation processes and structural changes in immunoactive biomolecules.

Based upon an analysis of the absorption spectra, the fluorescence and fluorescence excitation spectra, and the lifetime of the excited states of aqueous solutions (pH 7.4) of 2,3-dimethoxy-8-azagona-1,3,5(10),13-tetraene-12,17-dione, it is established that two centers of different type exist: one emits long-wave (L-centers) and the other short-wave (S-centers) fluorescence. Irradiation of solutions increases the number of L-centers and greatly decreases that of S-centers. Examination of the picosecond transient absorption spectra and their kinetics revealed that the initial photochemical stage is defined as the ionization of a considered molecule and the subsequent one, as the formation, most probably, of the dehydroderivative of a parent molecule. Copyright 2004 Wiley Periodicals, Inc. Biopolymers, 2004