Related Experiment Videos
Interaction between Ca2+ and dipalmitoylphosphatidylcholine membranes. II. Fluorescence anisotropy study
Biophysical Chemistry
|March 1, 1985
Summary
Calcium ions (Ca2+) restrict molecular mobility in dipalmitoylphosphatidylcholine membranes. This effect, observed even at low Ca2+ concentrations, suggests a long-range interaction influencing membrane properties.
Area of Science:
- Biophysics
- Membrane Biophysics
- Physical Chemistry
Background:
- Dipalmitoylphosphatidylcholine (DPPC) membranes are fundamental models for cell membranes.
- Understanding ion interactions with lipid bilayers is crucial for cellular function.
- Calcium ions (Ca2+) play vital roles in biological systems, including membrane dynamics.
Purpose of the Study:
- To investigate the impact of Ca2+ on molecular mobility within DPPC membranes.
- To elucidate the mechanism of Ca2+ interaction with lipid bilayers.
- To compare the effects of Ca2+ with those of other divalent cations like Mg2+.
Main Methods:
- Steady-state and time-resolved fluorescence anisotropy measurements.
- Utilizing 1,6-diphenyl-1,3,5-hexatriene (DPH) as a fluorescent probe.
- Analyzing fluorescence anisotropy decay in the hydrocarbon region of the membrane.
Main Results:
- Increased Ca2+ concentration led to restricted molecular rotation and reduced free volume.
- Decreased molecular mobility was evident starting from 1 mM Ca2+.
- Distinct differences in membrane property changes were observed between Ca2+ and Mg2+.
Conclusions:
- Ca2+ binding significantly alters DPPC membrane molecular mobility.
- A long-range attractive interaction between bound Ca2+ and phosphatidylcholine head groups is proposed.
- Ion-specific binding mechanisms are critical for modulating membrane properties.