TABLE 1.
ΔRP-e(0) and extrapolated distances of the phospholipid 31P to spin-label sites (rP-e) using a 2-μs τP-e
Samples were for SUVs of 5 mm PC/5 mm PMe with 14.4 μm PI-PLC added. In estimating distances, we assume that for the average size of these SUVs, two-thirds of the total lipid is in the outer monolayer and affected by the spin-label.
| PI-PLC | ΔRP-e(0) |
rP-ea |
||
|---|---|---|---|---|
| 31PC | 31PMe | 31PC | 31PMe | |
| s−1 | Å | |||
| W47C | 3.1 ± 0.7 | 5.6 ± 0.8 | 18.0 ± 0.7 | 16.3 ± 0.4 |
| H82C | 5.3 ± 1.0 | 9.2 ± 0.9 | 16.4 ± 0.5 | 15.0 ± 0.2 |
| Y118C | 4.1 ± 2.6 | 0 | 20.3 ± 2.2 | >30 |
| M121C | 0 | 0 | >30 | >30 |
| D205C | 17.6 ± 1.2 | 2.1 ± 1.0 | 13.5 ± 0.2 | 19.2 ± 1.7 |
| N220C | 0.2 | 0.16 | 28 ± 3 | 30 ± 4 |
| N243C | 4.7 ± 1.3 | 0.7 ± 0.4 | 16.8 ± 0.8 | 23.0 ± 2.6 |
| W280C | 3.0 ± 1.5 | 2.2 ± 0.7 | 18.1 ± 1.7 | 19.0 ± 1.0 |
a The errors in rP-e are estimated using a fixed τP-e, but looking at the range for the distance using the maximum and minimum ΔRP-e. For comparison, the values for spin-labeled W47C (different batches) at three different protein concentrations (0.25, 0.5, and 1 mg/ml) lead to 17.8 ± 1.3 Å for PC and 16.2 ± 1.0 Å for PMe.