Population shuffling of protein conformations

Area of Science:

• Protein dynamics
• Biophysics
• Structural biology

Background:

• Protein functions rely on molecular motions.
• Excited-state transitions (hundreds of microseconds) are well-studied.
• Ground-state protein dynamics remain largely unexplored.

Purpose of the Study:

• To investigate unexplored ground-state dynamics of proteins.
• To characterize motions on the microsecond timescale.
• To identify general mechanisms underlying protein plasticity.

Main Methods:

• Utilized newly developed high-power relaxation dispersion experiments.
• Detected motions on the microsecond timescale.
• Analyzed side-chain dynamics in ubiquitin and immunoglobulin G binding domain B.

Main Results:

• Identified microsecond timescale motions in protein hydrophobic cores and interaction surfaces.
• Observed plasticity in ubiquitin and immunoglobulin G binding domain B.
• Demonstrated population redistribution of side-chain rotamers (picosecond-nanosecond timescale).

Conclusions:

• Microsecond timescale motions are significant in protein ground states.
• Population shuffling is a likely general mechanism for protein plasticity.
• Advanced relaxation dispersion experiments enable new insights into protein dynamics.