Table 1.
Antimicrobial activity of the p4-based peptides
For each peptide, the following properties are specified: the amino acid sequence; the number of amino acid (aa) residues; the total charge at pH 6.0, which models the acidic environment of the water/bacterial membrane interface; and the relative mean hydrophobic moment, determined on the assumption of the spatial structure of the peptide as a twisted β sheet, which corresponds to the periodicity of 160° in the Edmundson projection (15). Peptides with aa substitutes are named based on first and last amino acid residue (the length), aa residue to be substituted, and substituting aa residue (bold). Cysteine with the thiol group blocked by IAA is underlined. Extra aa in the elongated form of p4 are italicized. d-VR15, VR15 comprised only of d-amino acid residues. The AM effect indicates killing activity of the listed peptides at 100 μm relative to p4 (100%), as determined by both MDA and RDA assays. +, >90%; −, <20%; +/−, ∼40%.
| Peptide name | Sequence | No. of aa | Total charge | rHMβ | AM effect (E. coli) |
|---|---|---|---|---|---|
| p4 | VRLEFKLQQTSCRKRDWKKP | 20 | +5 | 0.375 | + |
| scp4 | DPWLKVRKFQTLKQREKRCS | 20 | +5 | 0.033 | − |
| p4-IAA | VRLEFKLQQTSCRKRDWKKP | 20 | +5 | 0.375 | − |
| p4 sister peptides with residue substitutes | |||||
| (VP20)CA | VRLEFKLQQTSARKRDWKKP | 20 | +5 | 0.384 | − |
| (VP20)KA | VRLEFALQQTSCRARDWAAP | 20 | +1 | 0.409 | − |
| (VP20)KR | VRLEFRLQQTSCRRRDWRRP | 20 | +5 | 0.375 | + |
| Longer and shorter p4-based analogs | |||||
| VK23 | VRLEFKLQQTSCRKRDWKKPECK | 23 | +5 | 0.238 | +/− |
| VR15 | VRLEFKLQQTSCRKR- - - - - | 15 | +4 | 0.625 | + |
| RP19 | - RLEFKLQQTSCRKRDWKKP | 19 | +5 | 0.383 | + |
| LP18 | - - LEFKLQQTSCRKRDWKKP | 18 | +4 | 0.348 | − |
| EP17 | - - - EFKLQQTSCRKRDWKKP | 17 | +4 | 0.295 | − |
| FP16 | - - - - FKLQQTSCRKRDWKKP | 16 | +5 | 0.234 | − |
| KP15 | - - - - -KLQQTSCRKRDWKKP | 15 | +5 | 0.139 | − |
| d-VR15 | VRLEFKLQQTSCRKR- - - - - | 15 | +4 | 0.625 | + |