Figure 3.

tr-EPR signal generated by pulsed laser excitation (1-Hz repetition rate) of X. laevis (6–4) photolyase in the presence of potassium ferricyanide (2 mM) as an exogenous oxidant. EPR data were recorded at T = 278 K at 1.4 μs after laser-flash excitation in the direct-detection mode [integrated EPR amplitudes (dots) with A , enhanced absorption and E, emission]. Instrument settings: 9.6980 GHz; microwave power, 2 mW; optical sample excitation same as in Fig. 2. To obtain precise hyperfine line positions, the experimental spectrum was deconvoluted to a sum of 12 Gaussians (drawn lines). The arrows indicate the underlying hyperfine pattern of four nearly equivalent protons (for details, see text). Inset shows the corresponding light-initiated EPR signal observed in E. coli CPD photolyase (data taken from ref. 23).