Related Experiment Video
Updated: Jun 23, 2026
08:07
Assembly and Characterization of Biomolecular Memristors Consisting of Ion Channel-doped Lipid Membranes
Published on: March 9, 2019
Lipid-alamethicin interactions influence alamethicin orientation.
Biophysical Journal
|May 12, 2009
Summary
Alamethicin peptides switch between membrane surface and inserted states, explaining its nonconducting and conducting behavior. This phase transition is influenced by lipid/peptide ratio and water potential, resolving previous interpretations.
Area of Science:
- Biophysics
- Membrane protein structure and function
- Ion channel formation
Background:
- Conflicting interpretations exist regarding the nonconducting state of alamethicin in membranes.
- Previous studies suggested alamethicin molecules reside either on the membrane surface or within the hydrophobic core when not conducting.
- The barrel-stave configuration is widely accepted for the conducting state of alamethicin.
Purpose of the Study:
- To resolve conflicting interpretations of alamethicin's nonconducting state in lipid membranes.
- To investigate the phase-transitionlike behavior of alamethicin as a function of lipid/peptide ratio and water chemical potential.
- To elucidate the mechanism of alamethicin's voltage-gating behavior.
Main Methods:
- Utilized oriented circular dichroism (OCD) spectroscopy on aligned multilayer membrane samples.
- Investigated alamethicin behavior in the liquid crystalline L(alpha) phase.
- Varied lipid/peptide ratio (L/P) and chemical potential of water (mu) to monitor alamethicin states.
Main Results:
- Discovered a phase-transitionlike behavior where alamethicin switches between surface-bound and membrane-inserted states.
- Observed that high L/P ratio favors the surface state, while low L/P ratio leads to insertion at high mu.
- Found no significant change in alamethicin's secondary structure between surface and inserted states.
Conclusions:
- The observed phase transition explains the different interpretations of alamethicin's nonconducting state.
- Voltage-gating can be explained by surface-bound alamethicin molecules probabilistically inserting into the membrane via dipole-electric field interactions.
- The phase-transitionlike behavior likely arises from membrane-mediated intermolecular interactions between peptide molecules.
More Related Videos
Related Concept Videos
01:23Factors Affecting Protein-Drug Binding: Drug Interactions
Drug interactions are a critical aspect of pharmacology and can occur when two or more drugs compete for the same binding site. This competition can result in one drug displacing another, altering the effect of the displaced drug. Drug interactions are complex processes that rely heavily on how much of the displacer drug is present and how strongly it can bind to the same sites as the displaced drug.
Displacement interactions can have varying outcomes, ranging from toxicity to virtually...
Displacement interactions can have varying outcomes, ranging from toxicity to virtually...
01:25Pharmacokinetics: Drug–Drug Interactions
Drug interactions occur when the pharmacological effect of one drug is altered by another substance, either enhancing or diminishing its activity. The drug whose activity is altered is known as the object drug, and the substance causing the alteration is called the agent drug or the precipitant. The net effects of these interactions are mostly undesirable, leading to decreased effectiveness or increased adverse effects. In rare cases, interactions can be beneficial, such as the enhanced...
01:18Factors Affecting Protein-Drug Binding: Drug-Related Factors
Drug binding to proteins is a complex phenomenon influenced by various drug-related factors, each playing a significant role in the interaction between drugs and proteins within the body.
One crucial factor in drug-protein binding is the drug's lipophilicity or its affinity for fat. More lipophilic drugs tend to have higher binding extents. For example, highly lipophilic drugs like cloxacillin exhibit substantial protein binding, with as much as 95% of the drug binding to proteins. In contrast,...
One crucial factor in drug-protein binding is the drug's lipophilicity or its affinity for fat. More lipophilic drugs tend to have higher binding extents. For example, highly lipophilic drugs like cloxacillin exhibit substantial protein binding, with as much as 95% of the drug binding to proteins. In contrast,...
01:25Inhibitors of Bacterial Protein Synthesis
Aminoglycosides constitute a highly potent class of bactericidal antibiotics that exert their antimicrobial effects by targeting the bacterial ribosome, specifically disrupting protein synthesis. These polycationic molecules consist of amino-modified sugars linked via glycosidic bonds to an aminocyclitol core such as 2-deoxystreptamine or streptamine. Their strong positive charges facilitate tight binding to the negatively charged phosphate backbone of ribosomal RNA (rRNA), primarily at the 16S...
01:15Antifungal Agents
Amphotericin B is a broad-spectrum antifungal agent that exploits structural differences between fungal and mammalian cell membranes. Its amphipathic structure—featuring a hydrophobic polyene-lactone ring and a hydrophilic region containing mycosamine and carboxylic acid groups—enables selective binding to ergosterol, a sterol predominantly found in fungal plasma membranes. This selective interaction underlies the drug’s antifungal activity, although weak binding to cholesterol contributes to...
01:23Pharmacokinetic–Pharmacodynamic Relationship: Influence of Elimination Half-Life on Effect Duration
Drug elimination from the body primarily occurs through metabolic and excretion pathways. Hepatic metabolism transforms lipophilic drugs into hydrophilic forms for excretion, typically via enzymatic processes classified as phase I (modification) and phase II (conjugation). Renal excretion eliminates drugs and metabolites through filtration and secretion in the kidneys. Impairment in liver or kidney function can hinder these processes, delaying drug clearance and extending the drug’s half-life.