TABLE 2.
Peptide | POPC/POPE (90:10) |
POPC/POPE (80:20) |
POPC/POPE/POPG (60:20:20) |
POPC/POPE/Chol/SM (17:10:33:40) |
POPC/Chol/SM (27:33:40)a |
|||||
---|---|---|---|---|---|---|---|---|---|---|
P/L max | Kd | P/L max | Kd | P/L max | Kd | P/L max | Kd | P/L max | Kd(app) | |
μm | μm | μm | μm | μm | ||||||
kB1 | 0.18 ± 0.01 | 73 ± 9 | 0.24 ± 0.01 | 24 ± 0.5 | 0.29 ± 0.01 | 18 ± 1 | 0.11 ± 0.003 | 29 ± 2 | 0.11 | 2893 |
kB2 | 0.18 ± 0.03 | 19 ± 4 | 0.22 ± 0.01 | 16 ± 1 | 0.31 ± 0.01 | 15 ± 1 | 0.12 ± 0.004 | 13 ± 1 | 0.12 | 1586 |
kB6 | 0.23 ± 0.02 | 25 ± 3 | 0.31 ± 0.02 | 22 ± 2 | 0.35 ± 0.01 | 10 ± 1 | 0.13 ± 0.01 | 16 ± 2 | 0.13 | 594 |
kB7 | 0.20 ± 0.02 | 66 ± 15 | 0.34 ± 0.01 | 47 ± 2 | 0.37 ± 0.01 | 15 ± 1 | 0.13 ± 0.01 | 57 ± 6 | 0.13 | 1846 |
kB5 | 0.12 ± 0.003 | 6.6 ± 4 | 0.34b | 143 ± 42 | 0.28b | 18 ± 4 | 0.05 ± 0.003 | 11 ± 2 | 0.05 | 129 |
kB8 | 0.17b | 19 ± 3 | 0.34b | 190 ± 39 | 0.28b | 10 ± 2 | 0.14b | 112± 4 | 0.14 | 983 |
kB9 | 0.17b | 41± 7 | 0.10 ± 0.003 | 13 ± 1 | 0.08 ± 0.005 | 32 ± 5 | 0.08 | 143 | ||
cyO2 | 0.17 ± 0.003 | 8.2 ± 0.4 | 0.34 ± 0.01 | 8.6 ± 0.6 | 0.28 ± 0.004 | 3.8 ± 0.5 | 0.14 ± 0.002 | 24 ± 1 | 0.14 | 1283 |
tcA | 0.15 ± 0.01 | 41 ± 6 | 0.34b | 178 ± 12 | 0.24 ± 0.01 | 35 ± 4 | 0.08 ± 0.017 | 88 ± 48 | 0.08 | 700 |
a The binding of cyclotides to membranes lacking PE-phospholipids is weak; therefore, the curves do not reach a plateau in the concentration range tested, the P/Lmax cannot be defined, and nor can Kd value. Nevertheless to illustrate the weak affinity to membranes lacking PE, binding to POPC/Chol/SM is compared with POPC/POPE/Chol/SM assuming the same P/Lmax for both lipid mixtures (which possess identical fluidity properties at 25 °C). As this fit implies extrapolations, the error associated with the Kd is high, and therefore the fitted values are referred to as apparent Kd (Kd (app)).
b The curve did not reach a plateau in the concentration range tested; therefore, the P/Lmax was constrained to be equal to the value obtained with cyO2 which is also a bracelet cyclotide.