Atomic physics

Optics

Femtosecond

Spectroscopy

Raman spectroscopy

Quantum mechanics

Chromophore

Ultrashort pulse

Excited state

Chemical physics

Picosecond

Chemistry

Photochemistry

Physics

Laser

Nature Chemistry

Unveiling the nuclear motions of photoreceptor proteins in action is a crucial goal in protein science in order to understand their elaborate mechanisms and how they achieve optimal selectivity and efficiency. Previous studies have provided detailed information on the structures of intermediates that appear during the later stages (>ns) of such photoreception cycles, yet the initial events immediately after photoabsorption remain unclear because of experimental challenges in monitoring nuclear rearrangements on ultrafast timescales, including protein-specific low-frequency motions. Using time-domain Raman probing with sub-7-fs pulses, we obtain snapshot vibrational spectra of photoactive yellow protein and a mutant with high sensitivity, providing insights into the key responses that drive photoreception. Our data show a drastic intensity drop of the excited-state marker band at 135 cm−1 within a few hundred femtoseconds, suggesting a rapid weakening of the hydrogen bond that anchors the chromophore. We also ...

Probing the early stages of photoreception in photoactive yellow protein with ultrafast time-domain Raman spectroscopy