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Updated: May 13, 2026
11:37
Sigma's Non-specific Protease Activity Assay - Casein as a Substrate
Published on: September 17, 2008
Coacervates of lysozyme and β-casein
Skelte G Anema1, C G Kees de Kruif
1Fonterra Research Centre, Palmerston North, New Zealand.
Journal of Colloid and Interface Science
|March 21, 2013
Summary
Protein complexes form between lysozyme (LYZ) and beta-casein (BCN), creating coacervates that precipitate at charge neutrality. Salt and pH influence complex formation and size, with a proposed scaling law for prediction.
Area of Science:
- Biochemistry
- Colloid Science
- Food Science
Background:
- Protein-protein interactions are crucial in food systems.
- Lysozyme (LYZ) and caseins are key milk proteins.
- Complex coacervate formation is driven by electrostatic interactions.
Purpose of the Study:
- Investigate complex coacervate formation between lysozyme (LYZ) and beta-casein (BCN).
- Determine the influence of charge ratio, salt concentration, and pH on complexation.
- Propose a model to predict complex size and scattering intensity.
Main Methods:
- Titration of LYZ into BCN solutions.
- Varying salt (NaCl) concentrations and pH.
- Analysis of complex formation, precipitation, and re-dispersion.
- Scattering intensity measurements.
Main Results:
- Complex coacervates form between LYZ and BCN, leading to precipitation at the charge equivalent ratio (xcrit).
- Solubility is restored by NaCl, which also shifts xcrit.
- A scaling law predicts complex size and scattering intensity based on charge ratio.
- Complex formation occurs primarily on the BCN-rich side.
Conclusions:
- Electrostatic interactions govern LYZ-BCN complex coacervate formation.
- Salt and pH are critical parameters controlling complexation and solubility.
- The proposed scaling law offers a predictive framework for complex behavior.
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