TABLE 1.
Summary of physical and antimicrobial properties of cationic peptides and proteins
| Antimicrobial agent | Molecular mass (kDa) | Net chargea | Site of actionb | LD90 of wtc | MIC of wtd | Lysozyme sensitivity of wte | tagO/wt ratiof | Reference(s) |
|---|---|---|---|---|---|---|---|---|
| hNP1-3 | 3.5 | +2/+3 | CM | 100 | 1 | 36, 44 | ||
| Magainin II amide | 2.5 | +4 | CM | 10-40 | 10-40 | 1 | 24, 36; this study | |
| LL-37 | 4.5 | +6 | CM | 10 | 1 | 44, 50 | ||
| HBD-3 | ∼10g | +11 | CM | 10 | 10 | ∼10 | 24, 39; this study | |
| gIIA PLA2 | 14 | +15 | CM | 0.1 | 0.1 | ∼100 | 24; this study | |
| Lysozyme | 14.7 | +9 | CW | >5 × 104 | 1 | 2 | ||
| Lysostaphin | 25 | +10.5 | CW | 0.004 | 1 | 26, 43 | ||
| Lactoferrin | 80 | +11 | CMh | 500 | 1 | 44 |
(Lys + Arg) − (Asp + Glu).
CM, cell membrane; CW, cell wall.
The 90% lethal dose (LD90) (in micrograms per milliliter) was determined as described in the legend for Fig. 1.
MIC (in grams per milliliter) determined by Kusuma and Kokai-Kun (26).
Lysozyme sensitivity was determined by agar diffusion assay. Note that the growth of both strains was unaffected by 50 mg/ml of lysozyme.
Estimated difference in the resistance of wt and tagO strains of S. aureus to the indicated antimicrobial agent. This difference was calculated as the ratio of the estimated MIC, LD90, or lysozyme sensitivity of the indicated agent toward the tagO strain versus that of the wt parent strain.
HBD-3 is primarily found as a dimer (39).
The principal antistaphylococcal action of lactoferrin is likely mediated by sequestration of iron.