Cecropin A

A classic antimicrobial peptide from the giant silk moth, studied for its potent, selective activity against gram-negative bacteria.

Length: 37 amino acids
Half-life: Not well characterised
Mechanism: It functions by forming two amphipathic alpha-helices that interact with and permeabilize bacterial cell membranes, showing a preference for gram-negative bacteria.
Studied in: It is studied as a model antimicrobial peptide for its activity against gram-negative bacteria and its relative lack of lytic activity toward mammalian cells.

About Cecropin A

Cecropin A is a 37-amino-acid peptide originally isolated from the hemolymph of the pupal giant silk moth, Hyalophora cecropia. This cationic peptide is characterized by its structure, which consists of a long N-terminal amphipathic alpha-helix and a shorter, more hydrophobic C-terminal helix, connected by a flexible hinge.

This peptide is a widely used tool for investigating the mechanisms of selective antimicrobial action. Laboratory research focuses on its potent bactericidal effects, particularly against gram-negative organisms like E. coli, while exhibiting low toxicity in hemolysis assays. This selectivity makes it a valuable subject for biophysical studies comparing its interaction with bacterial versus mammalian model membranes.

Laboratory notes

The C-terminal amide is critical for its full spectrum of antimicrobial activity and stability.
Activity is most pronounced against gram-negative bacteria; it shows lower potency against gram-positive bacteria and fungi.
For comparative studies, its hemolytic activity should be measured alongside its minimum inhibitory concentration (MIC) against target bacteria.

Storage and reconstitution basics: storage guide.

Questions about Cecropin A

What gives Cecropin A its selectivity for bacterial membranes?

Its selectivity is thought to arise from its preference for membranes rich in negatively charged lipids (like phosphatidylglycerol), which are abundant in bacteria but not on the outer leaflet of mammalian cell membranes. Its relatively low hydrophobicity also contributes to its low hemolytic activity.

What is 'hemolymph'?

Hemolymph is the fluid, analogous to blood in vertebrates, that circulates in the interior of an insect's body, serving as a medium for the transport of nutrients, hormones, and immune effector molecules like Cecropin A.

How does Cecropin A's structure relate to its function?

The N-terminal helix is responsible for the initial electrostatic attraction to the bacterial membrane, while the more hydrophobic C-terminal segment is thought to penetrate the lipid core, leading to membrane disruption.

Is Cecropin A 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.