Antimicrobial · Linear alpha-helical peptide
Magainin II
A classic antimicrobial peptide from the African clawed frog, studied for its mechanism of bacterial membrane permeabilization.
- Length
- 23 amino acids
- Half-life
- Not well characterised
- Mechanism
- This cationic, amphipathic peptide forms alpha-helical structures that disrupt bacterial membranes by forming pores via the 'carpet' or 'toroidal pore' mechanism.
- Studied in
- Laboratory models use artificial lipid vesicles and live bacteria to study its membrane-disrupting activity and antimicrobial spectrum.
About Magainin II
Magainin II is a naturally occurring antimicrobial peptide originally isolated from the skin of the frog Xenopus laevis. It is a linear peptide of 23 amino acids that lacks cysteine residues and disulfide bonds. In the presence of lipid membranes, it adopts an amphipathic alpha-helical conformation, with hydrophobic and hydrophilic amino acids segregated on opposite faces of the helix.
Magainin II is a foundational model for studying the mechanism of action of pore-forming antimicrobial peptides. In vitro experiments using techniques like circular dichroism spectroscopy are used to confirm its conformational change from a random coil in solution to an alpha-helix upon binding to lipid vesicles. Its ability to induce leakage from these vesicles and its minimum inhibitory concentration (MIC) against various bacteria are primary endpoints in laboratory research.
Laboratory notes
- The peptide is unstructured in aqueous solution and folds into an alpha-helix only upon interaction with membranes or membrane-mimetic environments like SDS micelles.
- Activity is dependent on pH and salt concentration, which should be controlled and reported in antimicrobial assays.
- Readily soluble in water, but stock solutions should be stored frozen and undergo limited freeze-thaw cycles.
Storage and reconstitution basics: storage guide.
Questions about Magainin II
What does 'amphipathic' mean?
An amphipathic helix is a protein structure where one side of the helix is hydrophobic (water-repelling) and the other side is hydrophilic (water-attracting), enabling it to interact with both the lipid and aqueous components of a membrane environment.
What is the 'toroidal pore' model?
It's a model of membrane disruption where peptides insert into the membrane and induce the lipid monolayers to bend continuously through the pore, so that both the peptides and the lipid headgroups line the pore's interior.
Why is Magainin II a model peptide?
Its relatively simple, linear structure and well-documented mechanism of action make it an ideal tool for biophysical studies on peptide-membrane interactions and for use as a positive control in antimicrobial assays.
Is Magainin II for human use?
No. It is supplied strictly for in-vitro laboratory research and is not for human or animal consumption.
Related research peptides
All products are sold for laboratory research use only. Not for human consumption, not a medicine, not for diagnosing, treating or preventing any condition.