Angular-split/temporal-delay approach to ultrafast protein dynamics at XFELs.
1Renz Research Inc., Westmont, IL 60559, USA.
Summary
This study introduces a novel method using split X-ray pulses from free-electron lasers to cancel noise and capture ultrafast structural changes in biomolecules at atomic resolution.
Area of Science:
- Structural biology
- Biophysics
- Physical chemistry
Background:
- X-ray crystallography reveals electron-density changes linked to molecular structural dynamics.
- Free-electron lasers (FELs) offer femtosecond hard X-ray pulses for capturing ultrafast events.
- Self-amplified spontaneous emission (SASE) in FELs causes shot-to-shot fluctuations, hindering signal detection.
Purpose of the Study:
- To develop a method for noise reduction in X-ray crystallography experiments using FELs.
- To enable the study of ultrafast structural dynamics in biological macromolecules at atomic resolution.
Main Methods:
- Angularly splitting a single self-amplified spontaneous emission (SASE) pulse into two.
- Introducing a picosecond temporal delay between the split pulses.
- Using the split pulses to probe distinct states before and after laser-triggered photoexcitation.
Main Results:
- The proposed method cancels noise from shot-to-shot fluctuations by using split pulses from a single SASE pulse.
- This technique allows for the observation of two states (pre- and post-photoexcitation) using a single X-ray pulse event.
- Combined with serial crystallography, it facilitates atomic resolution studies of ultrafast dynamics.
Conclusions:
- This novel approach effectively overcomes the limitations of SASE noise in FEL-based X-ray crystallography.
- It provides a viable strategy for investigating light-initiated biochemical reactions and biological processes at unprecedented temporal and spatial resolution.
- Enables the study of subtle structural changes, including those without atomic displacement, at atomic resolution.
