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[Interaction of melittin with model membranes: effect on the size and permeability of liposomes]
Abstract:
The influence of melittin, a monomer devoid of the phospholipase activity, on the size and permeability of liposomes from egg lecithin (PC), dimyristoylphosphatidylcholine (DMPC) and dipalmitoylphosphatidylcholine (DPPC) has been investigated by the methods of fluorescence spectroscopy, quasi-elastic light scattering and freeze-fracture electron microscopy. While studying calcein release from liposomes under the influence of melittin it has been shown that binding of melittin with a bilayer is a fast process which depends on the concentration lipid: protein (Ri) ratio as well as on the phase state of the lipid. The lipids being in the liquid-crystalline forms (PC and DMPC) are characterized by a more rapid release of the dye-stuff from liposomes than DPPC vesicles being in gel state with the same Ri. Under the influence of different melittin concentrations heterogeneity of the system and its medium hydrodynamic size of particles at first increases (100 less than or equal to Ri less than 500) due to their fusion and then these parameters decrease to the initial values.
Insights
Melittin affects liposome size and permeability, with faster dye release from liquid-crystalline lipids (PC, DMPC) than gel-state lipids (DPPC). Liposome fusion increases size at specific melittin concentrations, then returns to baseline.
Area of Science:
- Biochemistry
- Biophysics
- Materials Science
Context:
- Liposomes are crucial for drug delivery and biomembrane research.
- Melittin, a peptide from bee venom, is known to interact with lipid bilayers.
- Understanding melittin-lipid interactions is key to controlling liposome properties.
Purpose:
- To investigate the effect of melittin on liposome size and permeability.
- To determine how lipid phase state influences melittin-induced changes in liposomes.
- To explore the relationship between melittin concentration and liposome fusion/aggregation.
Summary:
- Melittin's interaction with liposomes (egg lecithin, DMPC, DPPC) was studied using spectroscopy and microscopy.
- Melittin binding is rapid and depends on lipid:protein ratio and lipid phase state.
- Liquid-crystalline liposomes (PC, DMPC) showed quicker dye release than gel-state DPPC liposomes.
- Liposome fusion and increased hydrodynamic size were observed at specific melittin concentrations (100 ≤ Ri < 500), followed by a decrease.
Impact:
- Provides insights into melittin's mechanism of action on lipid bilayers.
- Highlights the role of lipid phase state in peptide-membrane interactions.
- Informs the design of liposomal drug delivery systems with controlled release properties.