Related Experiment Video
Updated: Aug 7, 2026
10:02
Neutron Spin Echo Spectroscopy as a Unique Probe for Lipid Membrane Dynamics and Membrane-Protein Interactions
Published on: May 27, 2021
Interactions of membrane-active peptides with thick, neutral, nonzwitterionic bilayers
Kandaswamy Vijayan1, Dennis E Discher, Jyotsana Lal
1Departments of Physics, of Chemical and Biomolecular Engineering, and of Physiology and Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
The Journal of Physical Chemistry. B
|July 21, 2006
Summary
Alamethicin, a peptide known for forming channels, interacts with and ruptures thick synthetic polymer membranes, extending membrane biophysics studies to new materials.
Area of Science:
- Membrane biophysics
- Polymer science
- Biochemistry
Background:
- Alamethicin is a well-characterized peptide that forms channels and permeabilizes cell membranes.
- Studies of peptide-membrane interactions have primarily focused on lipid bilayers (3-5 nm thick).
- Amphiphilic diblock copolymer bilayers offer distinct physicochemical properties, including greater thickness and variable charge.
Purpose of the Study:
- To investigate the interactions between alamethicin and other membrane-active peptides with novel diblock copolymer membranes.
- To extend the understanding of peptide-membrane interactions to synthetic, thicker membrane systems.
- To characterize how alamethicin interacts with and affects these synthetic bilayers.
Main Methods:
- Characterization of peptide-membrane interactions using biophysical techniques.
- Utilizing alamethicin and other membrane-active peptides.
- Employing amphiphilic diblock copolymer bilayers as model synthetic membranes.
Main Results:
- Alamethicin, despite being too small to span the copolymer bilayer, effectively interacts with these thicker synthetic membranes.
- The peptide causes rupture of the diblock copolymer membranes.
- These findings demonstrate peptide activity on a new class of synthetic membranes.
Conclusions:
- Alamethicin can interact with and disrupt thick, uncharged synthetic membranes composed of diblock copolymers.
- This study expands the scope of membrane biophysics to include synthetic polymer-based systems.
- Peptide-membrane interactions can occur even when the peptide does not span the entire membrane thickness.
Related Concept Videos
01:09Multi-pass Transmembrane Proteins and β-barrels
In multi-pass transmembrane proteins, the polypeptide chain crosses the membrane more than once. The transmembrane polypeptide chain either forms an α-helix or β-strand structure. α-Helix containing multi-pass transmembrane proteins are ubiquitous, whereas β-strand containing ones are mainly found in gram-negative bacteria, mitochondria, and chloroplasts.
α-Helix containing multi-pass transmembrane proteins
Multi-pass transmembrane proteins such as G-protein-linked receptors (GPCRs) and...
α-Helix containing multi-pass transmembrane proteins
Multi-pass transmembrane proteins such as G-protein-linked receptors (GPCRs) and...
01:35Asymmetric Lipid Bilayer
Biological membranes show uneven distribution of different types of lipids in the inner and outer layers, resulting in transverse asymmetric membranes. The treatment of the erythrocyte membrane with the enzyme phospholipase confirmed the asymmetric nature of the lipid bilayer. The enzyme hydrolyzes lipids into fatty acids and hydrophilic groups. The phospholipase acts only on the outer layer of the membrane, while the inner layer remains intact. The phospholipase treatment resulted in 80%...
01:16Introduction to Membrane Proteins
The cell membrane, or plasma membrane, is an ever-changing landscape. It is described as a fluid mosaic where various macromolecules are embedded in the phospholipid bilayer. Among the macromolecules are proteins. The protein content varies across cell types. For example, mitochondrial inner membranes contain ~76% protein content, while myelin contains ~18% protein content. Individual cells contain many types of membrane proteins—red blood cells contain over 50—and different cell types have...
01:24Protein Diffusion in the Membrane
Proteins show rotational as well as lateral diffusion across the membrane. The lateral diffusion of proteins was confirmed through the cell fusion experiment where mouse and human cells were fused, resulting in hybrid cells. When the human and mouse cells fused, the specific membrane proteins on human and mouse cells were marked with the red and green-fluorescent markers, respectively. Initially, the red and green fluorescence was located on the respective hemisphere of the cell. As time...
00:59Mechanisms of Membrane Domain Formation
Different physical properties of lipids and proteins allow them to localize and form distinct islands or domains in the membrane. Some membrane domains are formed due to protein-protein interactions, whereas others are formed due to the presence of specific lipids such as sphingolipids and sterols—for example, large proteins, such as bacteriorhodopsin, aggregate and create distinct domains.
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...
01:18Membrane Domains
The membrane domains concentrate specific lipids and proteins at one place within the membrane, which helps in cell signaling, adhesion, and other critical cellular processes. These domains can differ in size, composition, function, and lifespan.
Protein Domains
The membrane comprises a group of distinct proteins responsible for carrying out a cell's specific function. For example, the plasma membrane of the human sperm, or a single germ cell, contains a unique set of proteins in the anterior...
Protein Domains
The membrane comprises a group of distinct proteins responsible for carrying out a cell's specific function. For example, the plasma membrane of the human sperm, or a single germ cell, contains a unique set of proteins in the anterior...