Pressure-induced change in proteins studied through chemical modifications

Area of Science:

• Biochemistry
• Protein Chemistry
• Spectroscopy

Background:

• Proteins undergo structural changes in response to external stimuli like pressure.
• Understanding pressure-induced protein unfolding and refolding is crucial for food processing and biotechnology.
• Bovine alpha-lactalbumin (LA) and beta-lactoglobulin (LG) are major milk proteins with distinct structural properties.

Purpose of the Study:

• To investigate the pressure-induced structural modifications of bovine alpha-lactalbumin (LA) and beta-lactoglobulin (LG) at neutral pH.
• To compare the reversibility and extent of pressure-induced structural changes between LA and LG.
• To elucidate the differential effects of high pressure on protein structure and dynamics.

Main Methods:

• Fluorescence spectroscopy to monitor protein structure and dansylation.
• Circular Dichroism (CD) spectroscopy to assess secondary and tertiary structural changes.
• High-pressure application during protein modification and spectral analysis.

Main Results:

• High pressure significantly increased the dansylation rate and extent for beta-lactoglobulin (LG) compared to alpha-lactalbumin (LA).
• Structural changes in alpha-lactalbumin (LA) were largely reversible up to 400 MPa, while beta-lactoglobulin (LG) lost reversibility below 150 MPa.
• Differential effects on tryptophan fluorescence energy transfer indicated varying degrees of compactness in pressure-perturbed structures.

Conclusions:

• Alpha-lactalbumin (LA) and beta-lactoglobulin (LG) exhibit distinct pressure sensitivities and reversibility profiles.
• The structural differences account for the varied responses of LA and LG to high pressure.
• High-pressure studies provide insights into protein structural dynamics and stability relevant to biological and industrial applications.