Photolysis Mechanism of Aqueous Tyrosine Upon Excitation of the Second Absorption Band

Abstract—The formation mechanism of tyrosinyl radical was studied for aqueous solutions of tyrosine under irradiation at 235 nm which falls into the second absorption band. The work is based upon the analysis of the rate of bityrosine production for steady‐state excitation at low intensity. The results indicate that monophotonic O‐H bond cleavage of tyrosine, presumably involving the upper excited triplet state, is the initial photoprocess leading to the tyrosinyl radical when tyrosine is excited into the second absorption band.