TABLE 4.
Dichroic ratios, R, and order parameters, P2, of the lipid and peptide bands from DMPG + gramicidin A membranes
| Sym CH2
|
Asym CH2
|
C=O
|
Amide I
|
Amide A
|
|||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| T (°C)* | R | P2 | R | P2 | R | P2 | R | P2 | R | P2 | |
| Hydrated | 10 | 1.37 | 0.31 | 1.44 | 0.27 | 1.60 | 0.19 | 2.59 | 0.19 | – | – |
| 36 | 1.63 | 0.17 | 1.63 | 0.17 | 1.75 | 0.11 | 2.13 | 0.05 | 1.13 | −0.33 | |
| 40 | 1.66 | 0.16 | 1.60 | 0.19 | 1.76 | 0.11 | 2.12 | 0.04 | 0.75 | −0.53 | |
| Dried | 10 | 1.36 | 0.32 | 1.59 | 0.19 | 1.54 | 0.22 | 3.78 | 0.48 | 4.00 | 0.44 |
| 40 | 1.35 | 0.33 | 1.59 | 0.19 | 1.52 | 0.23 | 3.81 | 0.48 | 4.09 | 0.45 | |
Shown are the dichroic ratios, R, and order parameters, P2, of the lipid (CH2 symmetric and asymmetric stretch, and carbonyl stretch) and peptide (amide I and A) bands from DMPG + gramicidin A (10:1 mol/mol) membranes.
*
Order parameters, 〈P2(cos γ)〉, are calculated from Eq. 1, with orientations, Θ, of the transition moment given in Materials and Methods (see also Theoretical Background). For the amide A band, the mean effective orientation of the transition moment is calculated from the order parameters obtained from the amide I band in Tables 2–5, ΘA = 27°. The order of the entries corresponds to the chronology of the measurements.