Table 6.
The kinetic and affinity parameters from surface plasmon resonance analysis of the interaction of 32 µM tachyplesin I (TI) and cyclic tachyplesin I (cTI) with neutral (POPC) and negatively-charged model membranes (POPC/POPS (4:1)) and leakage induced by the same peptides and lipid systems.
| Peptide | Lipid System |
P/Lmax
(mol/mol) 1 |
KD
(µM) 1 |
koff (x 10−2 s−1) 2 |
P/Loff (mol/mol) 2 |
LCmax (%) 3 |
|---|---|---|---|---|---|---|
| TI | POPC | 0.26 ± 0.06 | 22.4 ± 10.9 | 1.50 ± 0.11 | 0.046 ± 0.001 | 39.5 ± 4.6 |
| cTI | 0.33 ± 0.07 | 16.7 ± 8.4 | 0.91 ± 0.03 | 0.065 ± 0.001 | 32.9 ± 9.4 | |
| TI | POPC/POPS (4:1) | 0.37 ± 0.04 | 11.8 ± 2.4 | 2.75 ± 0.22 | 0.096 ± 0.001 | 76.0 ± 2.8 |
| cTI | 0.48 ± 0.08 | 9.2 ± 3.4 | 0.70 ± 0.03 | 0.137 ± 0.002 | 58.5 ± 3.6 |
1 P/Lmax and KD were calculated from the dose-response curves (one-site specific binding with Hill slope equation, GraphPad Prism) in Figure 4b. The P/Lmax value represents the peptide-to-lipid ratio (mol/mol) when peptide-lipid binding reaches saturation, KD is the peptide concentration necessary to reach the half-maximal binding response. 2 koff is the dissociation constant and P/Loff is the peptide-lipid ratio at the end of association phase calculated from the sensorgrams obtained with 32 µM peptide in Figure 4a. koff and P/Loff were fitted in GraphPad Prism, assuming a Langmuir kinetic. 3 Percentage of leakage achieved when incubating 10 µM peptide with 5 µM LUVs. POPC is 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine; POPS is 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoserine.