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Interaction of Zn2+ with phospholipid membranes
H Binder1, K Arnold, A S Ulrich
1University of Leipzig, Institute of Medical Physics and Biophysics, Germany. binder@rz.uni-leipzig.de
Biophysical Chemistry
|April 26, 2001
Summary
Zinc ions bind to phospholipid membranes, altering headgroup structure and reducing hydration. This interaction stabilizes the lipid gel phase and enhances membrane fusion, suggesting zinc
Area of Science:
- Biophysics
- Membrane Biophysics
- Lipid Chemistry
Background:
- Phospholipid membranes are crucial for cellular function.
- Understanding ion interactions with lipids is key to membrane behavior.
- Zinc (Zn2+) is a divalent cation with known biological roles.
Purpose of the Study:
- To investigate zinc binding specificity to phospholipid headgroups.
- To characterize the effects of zinc on lipid hydration and phase behavior.
- To explore the implications of zinc-lipid interactions for membrane fusion.
Main Methods:
- Studied zwitterionic lipid 1-palmitoyl-2-oleoyl-phosphatidylcholine.
- Varied hydration levels at 30°C in the presence and absence of ZnCl2.
- Analyzed changes in lipid conformation, hydration shell, and phase behavior.
Main Results:
- Zinc forms a 2:1-1:1 complex with the lipid, primarily binding to phosphate groups.
- Zn2+ bridges stabilize the lipid gel phase over the liquid-crystalline state.
- Lipid headgroups lose hydration, becoming less hydrophilic, and adopt a trans/trans conformation.
- Energetic cost of headgroup dehydration decreases by ~10 kJ/mole with Zn2+.
- Zinc-bound phosphate interaction is predominantly covalent.
Conclusions:
- Zinc binding alters phospholipid headgroup structure and hydration.
- Dehydration of headgroups by zinc complexation enhances membrane fusogenic potency.
- Zinc is a potent divalent cation for inducing membrane fusion.