Human Beta-Defensin 3
Most potent human defensin with broad-spectrum activity including MRSA and VRE, and strong immunomodulatory properties.
Chemical Identity
| Property | Value |
|---|---|
| Gene | DEFB103B |
| Molecular Weight | ~5.2 kDa |
| Amino Acids | 45 (mature peptide) |
| Peptide Class | Beta-Defensin |
| Disulfide Bonds | 3 |
Structure
Human beta-defensin 3 (hBD-3) is a 45-amino acid cationic peptide with six cysteine residues forming three disulfide bonds. It has the highest net positive charge (+11) among human defensins, contributing to its potent antimicrobial activity. hBD-3 is expressed in skin, oral mucosa, pharynx, tonsils, and heart.
Mechanism of Action
hBD-3 kills microbes through rapid membrane disruption, with its high cationic charge enabling strong electrostatic interaction with anionic bacterial membranes. Unlike hBD-1 and hBD-2, hBD-3 maintains activity in physiological salt concentrations. It also activates dendritic cells through TLR1/2 signaling and has potent chemotactic activity.
Clinical Applications
- Skin infections: Active against MRSA and VRE
- Oral defense: Expressed in gingival epithelium
- Wound healing: Promotes keratinocyte migration
- Implant infections: Anti-biofilm activity
- Therapeutic potential: Topical formulation for resistant infections
Pharmacology
- Spectrum: Broadest of human defensins (gram-positive, gram-negative, fungi, enveloped viruses)
- Salt resistance: Maintains activity at physiological NaCl
- Anti-MRSA: Active against vancomycin-resistant strains
- Synergy: Works with LL-37 and conventional antibiotics
References
- Harder, J., et al. (2001). hBD-3: a novel human beta-defensin. Journal of Biological Chemistry, 276, 5707-5713.
- Garcia, J.R., et al. (2001). Human beta-defensin 3: broad antimicrobial activity. Proceedings of the National Academy of Sciences, 98, 1537-1542.
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