Kinetics of Electron Returns in Successive Two-Photon DNA Repair by (6-4) Photolyase

(6-4) photolyase is a flavoenzyme that catalyzes the chemically challenging repair of carcinogenic photoproduct lesions in DNA using sunlight. Nature may have overcome challenge by combining two distinct successive photoreactions, each starting with electron transfer from an excited flavin to lesion. We herewith report transient absorption study returns following chemical transformations successfully dissected kinetics finalize first and second photoreactions (∼40 μs ∼200 ns, respectively) Xenopus laevis, corroborating detailing two-photon reaction model.