Antimicrobial · Proline-rich, porcine cathelicidin-derived antimicrobial peptide
PR-39
Also known as Proline–arginine-rich peptide 39
A proline- and arginine-rich porcine peptide studied for bacterial intracellular activity and interactions with cellular proteins.
- Length
- 39 amino acids
- Half-life
- Not well characterised
- Mechanism
- PR-39 can enter susceptible bacteria and interfere with intracellular processes, including protein and DNA synthesis, without requiring extensive membrane lysis. In separate cell and biochemical models, interactions with SH3-domain proteins and modulation of proteasome-associated processes have also been reported; no single receptor explains all observed activities.
- Studied in
- Bacterial uptake and macromolecular-synthesis assays, SH3-domain binding experiments and cultured-cell proteasome studies investigate its distinct intracellular activities.
About PR-39
PR-39 was originally isolated from porcine small intestine and was subsequently identified in porcine neutrophils as a cathelicidin-derived peptide. Its name reflects its 39-residue length and unusually high content of proline and arginine. Unlike the cysteine-rich protegrins, PR-39 contains no disulphide-bonded β-hairpin scaffold. Its proline-rich sequence instead supports an extended structural character and protein-interaction motifs, making it a distinct research tool within the broader group of innate-defence peptides.
Bacterial studies distinguish PR-39 from strongly membrane-lytic peptides by examining cellular uptake and inhibition of macromolecular synthesis. Uptake determinants, including SbmA in susceptible bacterial systems, can influence experimental sensitivity. Separate biochemical and cultured-cell studies examine binding to SH3-domain-containing proteins such as p47phox, as well as effects on proteasome-associated protein turnover. These findings represent different experimental contexts and should not be collapsed into one universal mechanism or assumed to share an identical molecular target.
Laboratory notes
- For research use only; confirm that material is full-length PR-39 rather than an N-terminal fragment used in some mechanistic studies.
- Include uptake-deficient bacterial controls where available when testing whether activity depends on intracellular access.
- For protein-interaction assays, include unrelated proline-rich peptide controls and assess whether labels alter binding or uptake.
Storage and reconstitution basics: storage guide.
Questions about PR-39
Does PR-39 require disulphide folding?
No. PR-39 lacks cysteine residues and therefore does not require intramolecular disulphide formation. Its structural behaviour differs from that of β-hairpin peptides such as protegrins.
Why is SbmA relevant to bacterial experiments?
SbmA can facilitate entry of proline-rich antimicrobial peptides in susceptible bacteria. Comparing appropriate uptake-proficient and uptake-deficient strains helps assess the contribution of intracellular access.
Is inhibition of macromolecular synthesis proof of a direct molecular target?
No. Reduced protein or DNA synthesis is a functional readout and may include downstream effects. Direct target assignment requires additional binding, biochemical or genetic evidence.
Is PR-39 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.