A guide to time-resolved structural analysis of light-activated proteins.

Area of Science:

• Structural biology
• Biophysics
• Photochemistry

Background:

• Protein structural dynamics are crucial for function, occurring across diverse timescales.
• X-ray free electron lasers (XFELs) provide high temporal and spatial resolution for studying these dynamics.
• Light-activated proteins are ideal for time-resolved studies due to laser-triggered reactions.

Purpose of the Study:

• To review advances in time-resolved structural techniques for studying light-activated proteins.
• To elucidate the mechanisms of photochemistry and its coupling to biological output responses.
• To explore the potential impact of these methods on unstudied photoreceptors and photoenzymes.

Main Methods:

• Time-resolved serial femtosecond crystallography (SFX) for visualizing early chemical changes.
• Solution scattering techniques for observing slower, global structural changes.
• Utilizing laser pulses to trigger reactions in light-activated proteins.

Main Results:

• SFX enables visualization of early chemical changes in proteins on previously inaccessible timescales.
• Solution scattering provides insights into slower, global structural rearrangements.
• These methods have uncovered key mechanisms linking light absorption to protein function and output responses.

Conclusions:

• Time-resolved SFX and solution scattering are powerful tools for understanding light-activated protein mechanisms.
• These techniques offer direct visualization of photochemistry and its coupling to biological functions.
• Future applications may extend to a broader range of photoreceptors and photoenzymes.