The influence of CO group on photodeactivation processes in tryptophan

It has been found that action of the light in a longer wavelength region of the tryptophan triplet-triplet absorption in polar glass at 77 K leads to a reversible decrease of the phosphorescence intensity. This effect is accompanied by decreasing of a lifetime for phosphorescent state. It has been proved that a reversible decrease of tryptophan phosphorescence is a result of intermolecular process connected with deactivation of the triplet T1-state by CO fragment of the carboxyl group. It seems that the reversible decrease of phosphorescence might be connected with a sufficiently fast process, which competes with a vibronical T2 → T1 relaxation.