Table 5.
Biophysical Data
| hydrophobicityb |
aqueous pH 7 |
50% TFE |
Δ[θ]222 |
amphipathicityg |
||||||
|---|---|---|---|---|---|---|---|---|---|---|
| peptidenamea | net charge | pH 2tR | [θ]222c | % helixd | [θ]222c | TFE-aqueous | % helixd induced | Tpe (°C) | PAf (min) | pH 2 |
| With Specificity Determinants | ||||||||||
| D87(Lys1-6 Arg-1) | +9 | 143.2 | 10192 | 33 | 31308 | 21116 | 67 | 21.2 | 5.9 | 3.625 |
| D84(Lys1-6 Lys-1) | +9 | 138.1 | 8230 | 24 | 33653 | 25423 | 76 | 21.2 | 5.9 | 3.327 |
| D85(Lys1-6 Orn-1) | +9 | 134.7 | 4808 | 13 | 38423 | 33615 | 87 | 17.3 | 4.1 | 3.420 |
| D86(Lys1-6 Dab-1) | +9 | 115.8 | 1769 | 6 | 27923 | 26154 | 94 | 5.0 | 0 | 3.879 |
| D105(Lys1-6 Dap-1) | +9 | 127.9 | 5961 | 25 | 24192 | 18231 | 75 | 16.9 | 3.7 | 3.570 |
| D101(Lys1Ser26-5 Lys-1) | +8 | 140.3 | 2538 | 7 | 38538 | 36000 | 93 | 21.2 | 6.0 | 3.419 |
| D102(Lys 1Ser26-5 Dab-1) | +8 | 113.9 | 5962 | 25 | 23385 | 17423 | 75 | 5.0 | 0 | 3.842 |
| Without Specificity Determinants | ||||||||||
| D85(K13A/K16A)-(Lys1-6 Orn-1) | +7 | 188.7 | 9269 | 51 | 18038 | 8769 | 49 | 41.0 | 28.0 | 4.631 |
| D86(K13A/K16A)-(Lys1-6 Dab-1) | +7 | 158.3 | 2308 | 12 | 18731 | 16423 | 88 | 31.0 | 12.5 | 5.135 |
| D105(K13A/K16A)-(Lys1-6 Dap-1) | +7 | 172.3 | 9577 | 53 | 18038 | 8461 | 47 | 39.0 | 18.0 | 4.797 |
D denotes all amino acids in each peptide are in the D-conformation.
tR denotes retention time in RP-HPLC at pH 2 at a temperature of 25 °C and is a measure of overall peptide hydrophobicity.
The mean residue molar ellipticities [θ]222 (mdeg cm2/(dmol × res)) at a wavelength of 222 nm were measured at 25 °C in aqueous conditions (100 mM KC1, 50 mM Na2HPO4/NaH2PO4, pH 7.0) or in aqueous buffer containing 50% trifluoroethanol (TFE) by circular dichroism spectroscopy.
The helical content (as a percentage) of a peptide is relative to the molar ellipticity value of the peptide in the presence of 50% TFE. % helix induced is the increase in molar ellipticity (as a percentage) of the peptide in the presence of 50% TFE.
Tp, temperature at which maximum retention time is observed over the temperature range 5–77 °C.
PA denotes the self-association parameter (dimerization/oligomerization) of each peptide during RP-HPLC temperature profiling, which is the maximal retention time difference of (tRt – tR5 for peptide analogs) – (tRt – tR5 for control peptide RC) within the temperature range; tRt – tR5 is the retention time difference of a peptide at a specific temperature (tRt) compared with that at 5 °C (tR5). The sequence of the random coil control peptide (RC) is Ac-ELEKGGLEGEKGGKELEK-amide.
Amphipathicity was determined by calculation of the hydrophobic moment [Eisenberg et.al 1982]59 using hydrophobicity coefficients determined by RP-HPLC at pH 2.