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Surface potential of phosphatidylserine monolayers. I. Divalent ion binding effect
Biochimica Et Biophysica Acta
|August 17, 1978
Summary
Divalent ions bind to phosphatidylserine membranes, with manganese showing the strongest affinity. Even high concentrations did not fully neutralize the membrane
Area of Science:
- Biophysics
- Membrane biophysics
- Surface chemistry
Background:
- Phosphatidylserine is a key anionic phospholipid in cell membranes.
- Understanding divalent ion interactions with membranes is crucial for cellular processes.
- Surface potential measurements provide insights into ion-membrane interactions.
Purpose of the Study:
- To investigate the binding mechanisms of divalent ions to phosphatidylserine monolayers.
- To quantify the binding affinities of different divalent cations (Mg2+, Ca2+, Mn2+).
- To determine the influence of monovalent ions on divalent ion binding.
Main Methods:
- Measurement of surface potentials of phosphatidylserine monolayers.
- Application of simple ion binding theory.
- Experimental data analysis to derive association constants.
Main Results:
- The binding affinity order was determined as Mn2+ > Ca2+ > Mg2+.
- Complete charge neutralization of phosphatidylserine was not achieved even at high divalent ion concentrations.
- Divalent ion binding was dependent on the concentration of monovalent ions in the subphase.
Conclusions:
- Divalent ion binding to phosphatidylserine is specific and concentration-dependent.
- Monovalent ions modulate the extent of divalent ion binding.
- Radioisotope tracer methods may overestimate bound ion amounts due to contributions from the electrical double layer.