Table 1. Phage Display Hits, Derivatives Thereof, and Their Prevention of α-Cbtx Inhibition of nAChRs.
| peptide | sequence | fold prevention of α-Cbtx inhibitiona | affinityb | identified by |
|---|---|---|---|---|
| no peptide (α-cbtx alone) | 1.0 | |||
| 1 | Ac-HAKTYMWDGWYMPTSH-NH2 | 7.4 | 2 ± 2 μM | phage displayc |
| 2 | Ac-HVNTYMWDGRYMRTSH-NH2 | 1.0 | phage displayc | |
| 3 | H-NWAPAQHGQKWYMQDYTSLE-NH2 | 3.8 | phage displayd | |
| 4 | H-TSNTTPWQTSWELMYAQQNY-NH2 | 1.6 | phage displayd | |
| 5 | H-KPHTYINDHNFIQYDNQQWL-NH2 | not soluble | phage displayd | |
| 6 | H-YVTHPWIDWWDNEPYM-NH2 | not soluble | phage displayd | |
| 7 | H-GHHHRVYMTDVTEHFRWMGK-NH2 | 0.6 | phage displayd | |
| 8 | H-GHHHRVYMTDVTEHFRWWVN-NH2 | 0.5 | phage displayd | |
| 9 | TAMRA-HAKTYMWDGWYMPTSH-NH2 | not tested | 52 ± 3 μM | optimization |
| 10 | Ac-TYMWDGWYMPT-NH2 | 4.5 | optimization | |
| 11 | Ac-YMWDGWYM-NH2 | 6.9 | optimization | |
| 12 | [PEG]6-YMWDGWYM-NH2e | 6.2 | 26 ± 4 μM | optimization |
| 13 | [PEG]6-YMWDGW-OHe | 0.3 | optimization | |
| 14 | [PEG]6-YMWDGW-NH2e | 0.5 | optimization | |
| 15 | H-WDGWYM-[PEG]6e | 0.3 | optimization | |
| 16 | Ac-WDGWYM-[PEG]6e | 0.3 | optimization | |
| 17 | [PEG]6-YMWEGWYM-OHe | 4.8 | optimization | |
| 18 | [PEG]6-YM(Nal)DGWYM-OHe,f | 2.8 | optimization |
α-Cbtx (40 nM) inhibited ACh (100 μM) gated currents through nAChRs to 8 ± 2% their control level, which is here normalized to 1.0. In the presence of, e.g., peptide 1 (100 μM), α-Cbtx (40 nM) only inhibited ACh (100 μM) gated currents to 60 ± 18% of control, here normalized to 7.4-fold prevention of inhibition.
Kd value of 9 determined in fluorescence polarization (FP) saturation experiment (n = 2). Ki values for peptides 1 and 12 determined by inhibition of 9 binding to α-Cbtx in FP competition experiments (n = 6), only measured for two lead peptides.
After five rounds of selection by biopanning.
From deep sequencing of all phages.
PEG, polyethylene glycol.
Nal, 3-(2-naphthyl)-l-alanine.