Figure 1. Transient absorption spectra for gwCry1a.

A Transient absorption spectra for gwCry1a as a function of wavelength (monitoring beam) proves that radical pairs are produced in cryptochromes of a migratory bird. The five graphs reflect the optical properties of the sample at different times, t _delay, after the laser flash. The amplitude of the signals depends on the protein concentration. The spectra were obtained by averaging two time profiles (cf. Fig. 1B) centred at t _delay using a time window of 500 µs. The variation of the absorption signal is about 5%, which is estimated from the data at 0.5 ms from 500 to 600 nm. For a detailed analysis of the spectra, see main text. B Transient absorption time profiles for gwCry1a. A laser flash (indicated by the arrow) is given at time = 0. The transient signal is obtained by averaging 7 time-profiles for the 490–550 nm wavelength region (corresponding to the optical features framed in blue in Fig. 1A) in 10 nm steps (blue curve, left scale) and 9 time-profiles for the 550–630 nm region (corresponding to the optical features framed in red in Fig. 1A) in 10 nm steps (red, graph, right scale), respectively. Solid lines show the fitted single or double exponential decays. The laser flash leads to radical formation as reflected by positive changes in the absorption signal. Significant radical concentrations are detectable up to ∼25 ms. For further discussion, see main text.