Spectral Characteristics and Mechanism of Chemiluminescence From Tryptophan Solutions Induced by Uv‐irradiation

The spectral distribution of the chemiluminescence, fluorescence and phosphorescence of tryptophan aqueous solutions irradiated with high and low pressure mercury lamps has been measured. The blue emission bands in the region of 380–520 nm observed both in the chemi‐ and photoluminescence, as well as an absorbance increase at 230 and 330 nm, indicate oxidative degradation of tryptophan leading to the formation of derivatives of N‐formylkynurenine, xanthurenic and anthranilic acids. Red emission bands at 630 and 705 nm in the spectrum of the chemiluminescence, an enhancement of light intensity by D 2 O and its decrease by NaN 3 and DABCO suggest a partial contribution of O 2 ( 1 Δ g ) to the photooxidation and chemiluminescence of tryptophan. The enthalpy of the exergonic reactions, leading to the formation of luminescing products, was calculated to average ‐270 kJ‐mol.