Structural fluctuations in proteins revealed by time-resolved fluorescence spectroscopy

Area of Science:

• Biophysics
• Protein Dynamics
• Spectroscopy

Background:

• Proteins exhibit dynamic motions crucial for their function.
• Intrinsic fluorescence from tryptophan and tyrosine residues offers a window into these dynamics.
• Time-resolved fluorescence spectroscopy (TRFS) can probe motions on picosecond-nanosecond timescales.

Purpose of the Study:

• To investigate the effects of temperature and calcium binding on the internal dynamics of parvalbumin.
• To examine the influence of hydration on protein dynamics using TRFS.
• To correlate observed flexibility with environmental factors affecting protein structure.

Main Methods:

• Utilized time-resolved fluorescence spectroscopy (TRFS).
• Measured fluorescence intensity and anisotropy decays.
• Studied parvalbumin under varying temperatures and calcium concentrations.
• Investigated the impact of hydration levels on protein dynamics.

Main Results:

• TRFS successfully monitored protein motions on the picosecond-nanosecond timescale.
• Temperature and calcium binding significantly affected parvalbumin's internal dynamics.
• Hydration levels influenced fluorescence measurements, providing insights into side chain flexibility.
• Complementary data from intensity and anisotropy decays revealed environmental effects on protein structure.

Conclusions:

• TRFS is a powerful tool for assessing protein dynamics and flexibility.
• Environmental factors like temperature, ion binding, and hydration modulate protein internal motions.
• Flexibility of aromatic side chains is sensitive to the protein's environment, impacting overall structure.