Protein dynamics investigated by neutron scattering

Area of Science:

• Biophysics
• Photosynthesis Research
• Neutron Scattering

Background:

• Protein dynamics are crucial for biological functions.
• Understanding these dynamics aids in comprehending complex processes like photosynthesis.
• Investigating molecular motion at the picosecond timescale is challenging.

Purpose of the Study:

• To highlight incoherent quasielastic neutron scattering (QENS) as a powerful tool for studying protein dynamics.
• To apply QENS to investigate protein dynamics in photosynthesis, specifically in the light-harvesting complex II (LHC II) and photosystem II (PS II).
• To introduce a novel laser-QENS pump-probe technique for real-time structure-dynamics-function relationship analysis.

Main Methods:

• Incoherent quasielastic neutron scattering (QENS) using low-energy neutrons (1 meV
• Utilizing the high sensitivity of neutrons to hydrogen atom motion (picosecond timescale).
• Developing and applying a laser-QENS pump-probe technique for in situ measurements.

Main Results:

• QENS successfully characterized picosecond motions of hydrogen atoms in proteins.
• Diffusive protein dynamics were shown to be essential for Q(A)(-·) reoxidation by Q(B) above 240 K.
• The strong dependence of electron transfer on temperature and hydration was explained by protein dynamics.

Conclusions:

• QENS is a highly effective method for investigating protein dynamics, particularly in photosynthesis.
• Protein dynamics play a critical role in the efficiency of electron transfer in photosynthetic complexes.
• The new laser-QENS technique enables direct, real-time observation of structure-dynamics-function relationships.