Trehalose effect on low temperature protein dynamics: fluctuation and relaxation phenomena

Area of Science:

• Biophysics
• Protein Dynamics
• Spectroscopy

Background:

• Horseradish peroxidase (HRP) is a key enzyme studied for its dynamic properties.
• Protein dynamics are influenced by their surrounding environment, such as glycerol/buffer glasses.
• Trehalose is a disaccharide known to stabilize proteins.

Purpose of the Study:

• To investigate the effect of trehalose enrichment on spectral diffusion in horseradish peroxidase.
• To compare the dynamics of trehalose-enriched and trehalose-free glycerol/buffer glasses.
• To understand the role of water molecules and protein conformation in spectral dynamics.

Main Methods:

• Spectral diffusion experiments were conducted on trehalose-enriched glycerol/buffer-glass with metal-free mesoporphyrin IX-substituted HRP.
• Experiments were compared to those in pure glycerol/buffer-glass.
• Analysis involved power law fitting for relaxation and fluctuation dynamics.

Main Results:

• Trehalose significantly speeds up spectral diffusion broadening compared to trehalose-free glass.
• This acceleration is attributed to altered water molecule dynamics within the protein interior.
• Relaxation dynamics, manifesting as aging, are superimposed but unaffected by trehalose, following power laws.
• Mean square displacement in conformation space exhibits anomalous diffusion, indicating long correlation times.

Conclusions:

• Trehalose alters protein dynamics by influencing water molecule mobility, leading to faster frequency fluctuations.
• Protein relaxation dynamics are independent of trehalose enrichment.
• Proteins at low temperatures are nonergodic systems, characterized by long correlation times in their conformational dynamics.