| Abstract: | There has been considerable interest in the photochemistry of tryptophan in connection with ultraviolet inactivation of enzymes. Earlier flash photolysis work has demonstrated that the hydrated electron (e-aq) is an initial product in the irradiation of indole derivatives, accompanied by a longer-lived transient absorption near 500 nm attributed to an aromatic radical species1–5]. Similar transients were observed in a recent flash photolysis study of lysozyme6] in which it was proposed that inactivation is a consequence of electron ejection from 1 to 2 essential tryptophan residues in the active center. However, there has been uncertainty concerning the tryptophan radical structure and its relationship to the triplet state and radical spectra reported for tryptophan photolysis in low-temperature rigid media. This note reports a flash photolysis investigation of L-tryptophan (Trp) and 1-Methyl-L-tryptophan (1-MeTrp) undertaken to clarify these points. The flash photolysis apparatus and methods employed are described in Ref. 6]. |
