Table 1. Peptides designed and characterized in this study.
The helical register for the α helix is indicated, 'efgabcd'. Key: AUC, molecular weight relative to monomer mass from analytical ultracentrifugation; TM, midpoint of thermal unfolding transition measured by CD spectroscopy; ϕ, non-proteinogenic amino acid based on L-phenylalanine with the para substituents given in the peptide name. Variants with ϕ = 4-trifluoromethyl-, 4-iodo-, 4-bromo- and 4-chloro-phenylalanine were also made, but these aggregated in solution.
| Peptide | Sequence efgabcd efgabcd efgabcd |
AUC (x monomer) |
TM
(°C) |
|---|---|---|---|
| PPα-Tyr | Ac-PPTKPTKP GDNAT PEKLAKY QADLAKY QKDLADY-NH2 | 0.9 | 39 |
| PPα-Phe | Ac-PPTKPTKP GDNAT PEKLAKF QADLAKF QKDLADF-NH2 | 0.9 | 20 |
| PPα-Trp | Ac-PPTKPTKP GDNAT PEKLAKW QADLAKW QKDLADW-NH2 | 0.9 | 36 |
| PPα-His | Ac-PPTKPTKP GDNAT PEKLAKH QADLAKH QKDLADH-NH2 | ND | < 0 |
| PPα-ϕNH2 | Ac-PPTKPTKP GDNAT PEKLAKϕ QADLAKϕ QKDLADϕ-NH2 | 1.0 | 19 |
| PPα-ϕOCH3 | Ac-PPTKPTKP GDNAT PEKLAKϕ QADLAKϕ QKDLADϕ-NH2 | 1.0 | 38 |
| PPα-ϕCH3 | Ac-PPTKPTKP GDNAT PEKLAKϕ QADLAKϕ QKDLADϕ-NH2 | 0.8 | 31 |
| PPα-ϕF | Ac-PPTKPTKP GDNAT PEKLAKϕ QADLAKϕ QKDLADϕ-NH2 | 1.0 | 26 |
| PPα-ϕCN | Ac-PPTKPTKP GDNAT PEKLAKϕ QADLAKϕ QKDLADϕ-NH2 | 0.9 | 22 |
| PPα-ϕNO2 | Ac-PPTKPTKP GDNAT PEKLAKϕ QADLAKϕ QKDLADϕ-NH2 | 1.1 | 17 |