Related Experiment Videos
Direct determination of the calcium profile structure for dipalmitoyllecithin multilayers using neutron diffraction
Biophysical Journal
|December 1, 1984
Summary
Calcium distribution in dipalmitoyllecthin (DPPC) multilayers was mapped using neutron diffraction. Results show calcium localizes to phospholipid headgroups, not the hydrocarbon core, influencing bilayer structure.
Area of Science:
- Biophysics
- Materials Science
- Structural Biology
Background:
- Dipalmitoyllecthin (DPPC) forms lamellar phases crucial for biological membranes.
- Understanding ion distribution in lipid bilayers is key to membrane function.
Purpose of the Study:
- To precisely determine calcium distribution within DPPC lamellar phases.
- To elucidate the interaction of calcium with phospholipid headgroups.
Main Methods:
- Neutron diffraction with stable isotope substitution (44Ca for 40Ca).
- Analysis of lamellar diffraction patterns and difference profiles.
- H2O/D2O exchange for water profile determination.
Main Results:
- Calcium isotopes induced significant resonance effects on diffraction intensities.
- Calcium was localized to the phospholipid headgroup region, excluding the hydrocarbon core.
- Reciprocal space analysis revealed calcium binding within 1-2 Å of the phosphate moiety.
Conclusions:
- Calcium ions preferentially bind to the phosphate groups of DPPC bilayers.
- This localization influences the structural organization of lipid headgroups.
- Neutron diffraction with isotope substitution is effective for mapping ion distribution in lipid systems.