Antimicrobial · Disulphide-stabilised α-defensin
Human alpha-defensin 5 (HD-5)
Also known as HD5; DEFA5
A 32-residue Paneth-cell α-defensin studied for disulphide-dependent structure, microbial membrane interactions and viral capsid binding.
- Length
- 32 amino acids
- Half-life
- Not well characterised
- Mechanism
- Mature HD-5 interacts with microbial surfaces and can disrupt membrane integrity, although its activity depends on the organism and assay environment. Antiviral model studies also describe capsid binding and interference with viral entry or uncoating; no single obligatory receptor accounts for its antimicrobial actions.
- Studied in
- Laboratory studies use bacterial cultures, membrane systems, intestinal organoids and transgenic mouse models to investigate Paneth-cell defence, microbial community interactions and pathogen entry.
About Human alpha-defensin 5 (HD-5)
Human α-defensin 5 is encoded by DEFA5 and is particularly associated with Paneth cells at the base of small-intestinal crypts. Identified through studies of intestinal defensin expression, it is produced as a 94-residue precursor containing a signal peptide and prosegment. Proteolytic processing generates the canonical 32-residue mature peptide. Its six cysteines form three intramolecular disulphide bonds, with the characteristic α-defensin connectivity linking cysteines I–VI, II–IV and III–V.
The mature peptide adopts a compact, β-sheet-rich fold and can form dimers and higher-order assemblies under suitable conditions. Bacterial experiments examine membrane permeabilisation alongside interactions with cell-envelope components, while virology models distinguish effects on enveloped and non-enveloped particles. Activity is not uniformly predicted by positive charge alone: folding, oligomerisation, ionic strength and microbial surface chemistry all matter. Transgenic intestinal models have also been used to examine how HD-5 expression influences microbial community composition.
Laboratory notes
- Confirm whether the material is mature HD-5 or a precursor-derived fragment, and verify both molecular mass and disulphide connectivity.
- Control ionic strength, pH and protein content in antimicrobial assays; these variables can substantially alter apparent activity.
- Use low-binding labware and assess recovery after dilution, as surface adsorption can distort low-concentration experiments.
Storage and reconstitution basics: storage guide.
Questions about Human alpha-defensin 5 (HD-5)
Is mature HD-5 the same as pro-HD-5?
No. Pro-HD-5 retains an N-terminal prosegment, whereas canonical mature HD-5 contains 32 residues. Processing state changes its physicochemical behaviour and must be specified.
Does HD-5 act through a defined antimicrobial receptor?
No single obligatory receptor is established. Its antimicrobial effects involve interactions with microbial envelopes or viral structures, with different mechanisms across experimental systems.
Why does disulphide mapping matter?
Correct mass alone does not establish the native fold. Alternative disulphide pairings can change structure, proteolytic stability and assay behaviour.
Is Human alpha-defensin 5 (HD-5) 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.