Time resolved transient circular dichroism spectroscopy using synchrotron natural polarization.

Area of Science:

• Biophysics
• Spectroscopy
• Structural Biology

Background:

• Ultraviolet (UV) synchrotron radiation circular dichroism (SRCD) spectroscopy is crucial for determining biomolecular structure.
• Current SRCD methods have limitations in accessing ultrafast time scales.
• Other techniques like IR, NMR, fluorescence, absorbance, and SAXS measure rapid events.

Purpose of the Study:

• Introduce and validate a novel time-resolved SRCD (tr-SRCD) technique.
• Overcome limitations of existing broadband UV SRCD setups.
• Enable the study of biomolecular dynamics at nanosecond timescales.

Main Methods:

• Developed a tr-SRCD setup utilizing the natural polarization of synchrotron radiation.
• Achieved significantly improved acquisition speed (10 mHz to 130 Hz).
• Demonstrated the technique by tracking azopeptide photoisomerization.

Main Results:

• tr-SRCD provides temporal resolution orders of magnitude better than previous SRCD methods.
• Successfully monitored isomer concentration changes following photoisomerization.
• The technique enables measurements on ultrafast timescales previously inaccessible to SRCD.

Conclusions:

• tr-SRCD represents a breakthrough in SRCD spectroscopy.
• The technique opens new avenues for characterizing rapid biological processes.
• Potential applications include studying protein folding and protein-ligand binding dynamics.