TABLE 3.
Microbicidal activities of peptidesa
| Amino acid position | Residue replaced by alanine | MMC99 μg/ml |
P valueb | |||||
|---|---|---|---|---|---|---|---|---|
| BHIdil |
BP |
|||||||
| E. coli | S. aureus | C. albicans | E. coli | S. aureus | C. albicans | |||
| 20 | C | >25 | 14 | 12 | >100 | >100 | >100 | |
| 21 | F | 12 | 7 | 12 | ND | ND | ND | |
| 22 | Q | 6 | 3.5 | 6 | 50 | 100 | 25 | |
| 23 | W | 25 | 14 | 12 | >100 | >100 | >100 | |
| 24 | Q | 12 | 3.5 | 12 | 50 | 100 | 50 | |
| 25 | R | 12 | 7 | 12 | ND | ND | ND | |
| 26 | N | 6 | 3.5 | 6 | 25 | 50 | 25 | <0.05 |
| 27 | M | 12 | 3.5 | 25 | 50 | >100 | 50 | |
| 28 | R | 25 | 7 | 25 | >100 | >100 | >100 | |
| 29 | K | 12 | 3.5 | 25 | 100 | >100 | >100 | |
| 30 | V | 12 | 3.5 | 25 | 50 | >100 | 50 | |
| 31 | R | 12 | 7 | 25 | >100 | >100 | >100 | |
| None | None | 12 | 7 | 12 | 100 | >100 | 50 | |
a
Shown are microbicidal activities of peptides derived from amino acid residues 20-31 (CFQWQRNMRKVR) by alanine scan. Peptides were incubated with C. albicans, E. coli O6K5, and methicillin-resistant S. aureus MRS3525 in BHIdil or BP. The peptide concentrations were serially diluted in twofold steps, starting with 25 or 28 μg/ml (S. aureus) using BHIdil and 100 μg/ml using BP as growth medium. All samples were run in duplicate. ND, not determined.
b
Values were determined using the Friedman test with Dunn's multiple comparison test. Each Ala-modified peptide was compared with the natural peptide sequence.