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Evolution of Interactions in the Protein Solution As Induced by Mono and Multivalent Ions
Sugam Kumar1,2, Indresh Yadav1, Debes Ray1
1Solid State Physics Division , Bhabha Atomic Research Centre , Mumbai 400 085 , India.
Biomacromolecules
|March 26, 2019
Summary
Adding multivalent ions to bovine serum albumin (BSA) solutions causes unique phase transitions. Higher-valent ions induce attractions and fractal aggregates, leading to reentrant phase behavior not explained by standard theories.
Area of Science:
- Biophysics
- Colloid and Surface Science
- Protein Chemistry
Background:
- Understanding protein-solution interactions is crucial for various applications.
- The behavior of proteins like bovine serum albumin (BSA) is influenced by counterions.
- Existing theories like DLVO theory explain some, but not all, protein-ion interactions.
Purpose of the Study:
- To investigate the effect of mono and multivalent counterions on BSA protein solution interactions.
- To explore phase transitions and aggregation behavior induced by different ion valencies.
- To compare experimental results with the predictions of DLVO theory.
Main Methods:
- Small-angle neutron scattering (SANS) for structural analysis.
- Dynamic light scattering (DLS) for particle size and interactions.
- Zeta-potential measurements for surface charge characterization.
Main Results:
- Monovalent and divalent ions lead to attractive interactions but maintain a one-phase system, consistent with DLVO theory.
- Trivalent and tetravalent ions induce a reentrant phase transition (one-phase to two-phase and back to one-phase).
- Higher-valent ions cause short-range attractions, fractal protein aggregates, and charge reversal in BSA solutions.
Conclusions:
- DLVO theory adequately describes BSA behavior with mono and divalent ions.
- Trivalent and tetravalent ions induce complex phase behavior due to ion-induced attractions and charge reversal.
- The interplay between electrostatic repulsion and ion-induced attraction governs the phase behavior of BSA in the presence of multivalent ions.
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