Antimicrobial · Linear, cationic amphipathic antimicrobial peptide
Magainin I
Also known as Magainin 1
A 23-residue frog-skin peptide used to investigate membrane-induced helicity and antimicrobial membrane disruption.
- Length
- 23 amino acids
- Half-life
- Not well characterised
- Mechanism
- Magainin I associates preferentially with anionic lipid membranes and adopts an amphipathic α-helical conformation that promotes membrane permeabilisation. Its activity is primarily membrane-mediated rather than dependent on a defined protein receptor.
- Studied in
- Bacterial cultures, dye-loaded lipid vesicles and membrane spectroscopy models are used to investigate lipid selectivity, peptide folding and membrane leakage.
About Magainin I
Magainin I belongs to the magainin family identified in skin secretions of the African clawed frog, Xenopus laevis, in 1987. Its sequence is GIGKFLHSAGKFGKAFVGEIMKS, with a free C-terminal carboxyl group in the native peptide. The sequence contains several lysine residues but no cysteine, so it lacks disulphide bonds. Magainin I is closely related to Magainin II, although their sequence differences mean that experimental findings should not automatically be treated as interchangeable.
In aqueous solution, the peptide is relatively unstructured; membrane-like environments favour an amphipathic α-helix. Electrostatic attraction to negatively charged lipids helps concentrate it at membrane surfaces, where peptide accumulation can disturb lipid packing and increase permeability. Vesicle leakage, circular dichroism and bacterial membrane assays examine these processes. Although pore-based mechanisms are frequently discussed for magainins, their behaviour depends on lipid composition and experimental conditions, and evidence obtained specifically with Magainin II requires careful attribution.
Laboratory notes
- For research use only; verify sequence identity and C-terminal chemistry because Magainin I and Magainin II are distinct assay reagents.
- Record buffer pH, ionic strength and lipid composition, as each can influence membrane binding and apparent antimicrobial activity.
- Use peptide-free leakage controls and matched solvent controls; adsorption to laboratory plastics can alter the effective peptide concentration.
Storage and reconstitution basics: storage guide.
Questions about Magainin I
Does Magainin I bind a specific receptor?
No established protein receptor is required for its principal membrane-permeabilising activity. Interactions with membrane lipids are central to the experimental mechanism.
Is Magainin I disulphide-stabilised?
No. Its 23-residue sequence contains no cysteine, and its membrane-associated structure is principally α-helical.
Can Magainin II data be assigned directly to Magainin I?
Not without qualification. They differ at two sequence positions, so membrane activity and structural results should be attributed to the peptide actually tested.
Is Magainin I 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.