Pressure-aided proteolysis of beta-casein

Area of Science:

• Protein chemistry
• Biochemistry
• Food science

Background:

• Beta-casein exists as micelles under atmospheric pressure.
• Protein hydrolysis aims to improve protein accessibility.
• Proteolytic enzymes like trypsin and chymotrypsin have different specificities.

Purpose of the Study:

• To investigate the effect of pressure treatment on beta-casein hydrolysis.
• To understand how pressure influences enzyme specificity and substrate accessibility.
• To analyze the resulting peptide profiles and their properties.

Main Methods:

• Hydrolysis of beta-casein using trypsin and chymotrypsin under varying pressures.
• Analysis of peptide profiles using reversed-phase chromatography.
• Measurement of enzyme activity after pressure treatments.

Main Results:

• Pressure inactivated trypsin, affecting hydrophilic segment hydrolysis.
• Chymotrypsin hydrolysis under pressure yielded novel peptides, suggesting altered mechanisms.
• Pressure did not change the reaction mechanism for trypsin, likely due to accessible hydrophilic regions.
• Pressure altered chymotrypsin's mechanism, impacting hydrophobic segment hydrolysis and generating new peptides.

Conclusions:

• Pressure treatment significantly impacts beta-casein hydrolysis differently depending on the enzyme used.
• Trypsin inactivation under pressure explains observed peptide profile differences.
• Chymotrypsin's altered hydrolysis mechanism under pressure leads to unique peptide generation with potentially different properties.
• Pressure can be a tool to modulate enzymatic hydrolysis for specific protein modifications.