Ultrafast time-resolved laser-spectroscopic characterization of flavins in blue-light photo-receptors

Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) containing blue-light sensitive photoreceptors (LOV domains, cryptochromes, BLUF domains) will be expressed by biologists of the consortium (P. Hegemann, A. Batschauer, W. Gärtner, E. Wolf). We want to study the ultrafast photo-physical and photo-chemical dynamics of the chromophores in the photoreceptor domains on a femtosecond to nanosecond timescale. Besides time-resolved fluorescence studies (fluorescence up-conversion, fluorescence amplification) and pump-probe absorption dynamics studies (singlet excited state and triplet excitedstate absorption dynamics, photo-isomerisation, photo-induced energy transfer and electron-transfer) there will be undertaken a steady-state fluorescence spectroscopic characterisation (quantitative fluorescence quantum distribution, absolute fluorescence quantum yields, degree of fluorescence of polarisation), fluorescence excitation spectroscopic characterisation (revealing of sample composition and relaxation channels), and absorption spectroscopic characterisation. The experimental results will be tried to simulate with theoretical models to get an understanding of the early dynamics in the photo-cycle of the receptors from excitation to reaction to back-transfer.