β-Lactoglobulin associative interactions: a small-angle scattering study

Area of Science:

• Biochemistry
• Protein Science
• Physical Chemistry

Background:

• Beta-lactoglobulin (β-lg) is a key lipocalin protein involved in molecular transport.
• Protein conformation stability is crucial for industrial applications.
• Understanding β-lg behavior in solution is essential for its use in various sectors.

Purpose of the Study:

• To investigate the conformation stability of beta-lactoglobulin (β-lg) in solution.
• To determine the effects of protein concentration, pH, NaCl, and temperature on β-lg structure.
• To elucidate the conditions influencing β-lg dimeric structure and stability.

Main Methods:

• Small-angle X-ray scattering (SAXS) was employed to analyze protein structure.
• Small-angle neutron scattering (SANS) was used to study β-lg conformation.
• Experiments were conducted in 50 mM HEPES buffer under varying conditions.

Main Results:

• Beta-lactoglobulin (β-lg) forms stable dimeric structures in 50 mM HEPES buffer across tested conditions.
• High protein concentrations (10-40 mg/mL) at pH 5.9 maintained the dimeric form.
• NaCl addition caused swelling at 20 mg/mL, while higher concentrations reduced the radius of gyration.
• Increasing acidity (pH 3.6) increased the radius of gyration, while neutral to alkaline pH decreased it.

Conclusions:

• Beta-lactoglobulin (β-lg) predominantly exists as a dimer in 50 mM HEPES buffer under diverse conditions.
• Protein conformation is sensitive to pH and salt concentration, exhibiting swelling and changes in dimensions.
• The findings provide insights into β-lg stability, relevant for its industrial applications.