TABLE 1.
Structural and functional characterization of linear and stapled peptides
| Peptide | Ellipticity, CD spectra, (MRE222 nm)a | Ethidium efflux, rel. rateb | Ethidium resensitization, MICERc | Antimicrobial activity, MICAAc | Hemolytic activity, MHCd |
|---|---|---|---|---|---|
| μm | |||||
| TM4 | −30,300° | 0.37 | 1.25 | > 40 | 12.5 |
| TM4(90–98) | −18,300° | 0.91 | >20 | > 40 | > 200 |
| TM4(89–99) | −18,600° | 0.87 | >20 | >40 | >200 |
| TM4(88–100) | −32,100° | 0.51 | 5–10 | 20 | >200 |
| TM4(88–100)-N95 | −26,200° | 0.90 | >20 | >40 | >200 |
| TM4(88–100)scr | −20,000° | 1.07 | 20 | 40 | NDe |
| S-TM4(88–100) | −32,100° | 0.24 | 0.63–1.25 | 5 | 12.5 |
| S-TM4(88–100)-G95 | −26,200° | 0.56 | 1.25–2.5 | 10 | 25 |
| S-TM4(88–100)-N95 | −28,700° | 0.67 | 1.25–2.5 | 20 | >200 |
| S1-TM4(88–100)-N95 | −25,700° | 0.52 | 0.31 | 5 | 100 |
| S2-TM4(88–100)-N95 | −30,400° | 0.60 | 0.31–0.63 | 5 | 100 |
a MRE = mean residue molar ellipiticity (deg cm2 dmol−1) in circular dichroism spectra at 222 nm, recorded on samples of 20 μm peptide in 20 mm SDS. See also Fig. 3.
b For each experiment, relative efflux rate constants were determined using first-order exponential decay and normalized to ethidium efflux in Hsmr-expressing E. coli BL21(DE3) cells without addition of peptide (kaverage = 2.4 ± 0.4 s−1 with n = 11). Cells not expressing Hsmr have a relative efflux rate of 0.15 ± 0.02 (25).
c Minimal inhibitory concentration (MIC) represents the lowest concentration at which bacterial growth of Hsmr-expressing E. coli BL21(DE3) was completely inhibited with (MICER) or without (MICAA) the presence of ethidium bromide. See “Materials and Methods” for further details.
d MHC is the lowest concentration at which hemoglobin concentrations reached at least 10% of the positive control.
e ND, not determined.