Table 2.
Oxygen Permeability, Partitioning, and Related Data for Bilayers Composed of POPC and/or Cholesterol
| Cholesterol Content % | PM (cm/s) | Experimental PM (cm/s) | PM/Pwa | Bilayer Thickness, DHH (Å) | Escape Threshold, ±h/2 (Å) | Escape Rate, Φesc (×10−4 molecules/ps) | O2 Population in Water, Nw (×10−2 molecules/Å) | [O2] in Water, Cw (mM) | Partition Coefficient, KP |
|---|---|---|---|---|---|---|---|---|---|
| 0 | 52 ± 2 | 157.4b | 1.12 ± 0.04 | 38.0 | ±28 | 7.96 ± 0.06 | 7.60 ± 0.23 | 30.50 ± 0.93 | 8.0 ± 0.5 |
| 12.5 | 47 ± 2 | — | 1.09 ± 0.05 | 39.8 | ±30 | 8.15 ± 0.26 | 8.65 ± 0.32 | 39.11 ± 1.46 | 6.4 ± 0.4 |
| 25 | 48 ± 3 | — | 1.11 ± 0.06 | 44.0 | ±30 | 7.97 ± 0.09 | 8.32 ± 0.44 | 42.64 ± 2.28 | 6.2 ± 0.1 |
| 37.5 | 46 ± 2 | — | 1.10 ± 0.05 | 44.5 | ±31 | 8.40 ± 0.00 | 9.08 ± 0.38 | 51.58 ± 2.15 | 5.2 ± 0.1 |
| 50 | 43 ± 3 | 49.7b | 0.99 ± 0.06 | 45.5 | ±30 | 8.12 ± 0.02 | 9.47 ± 0.58 | 57.78 ± 3.51 | 5.0 ± 0.0 |
| 62.5 | 40 ± 2 | — | 0.92 ± 0.04 | 45.0 | ±30 | 7.03 ± 0.05 | 8.81 ± 0.38 | 56.10 ± 2.39 | 5.1 ± 0.0 |
| 100c | 10 ± 2 | 15.9d | 0.20 ± 0.04 | 24.3 | ±26 | 1.58 ± 0.28 | 7.55 ± 0.46 | 51.41 ± 3.12 | 6.9 ± 1.1 |
Simulations at 37°C. Shown are mean values ± SD.
a
Pw calculated using Eq. 4 with the experimental Dw value of 2.60 × 10−5 cm2/s.
b
Probe-based spin-relaxation EPR experiments at 35°C (19).
c
Metastable mimic of the noncrystalline cholesterol bilayer domain.
d
Probe-based spin-relaxation EPR experiments at 25°C (24).