Table 1.
Summary of FRET Data and Comparison of X-ray and FRET-Derived Distances
| C3bAx488:FH1-4Ax555 | C3bAx647:FH1-4Ax555 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Pair | D (X-ray)a (Å) | Averageb τ (ns) | Efficiencyav | Dav (Å)c | Dmin (Å) | Dmax (Å) | Avd. τ (ns); don. vs. don. +acc. | Efficiencyav | 3Dav (Å) | Dmin (Å) | Dmax (Å) |
| C3bAx488 (alone) | – | 1.87 ± 0.04 | |||||||||
| C3bAx488: CCP 1 [N29CAx555] | 123 | 1.79 ± 0.05 | 4.4 ± 3.6 | 102 | 92 | 137 | |||||
| C3bAx488: CCP 2 [N102CAx555] | 102 | 1.73 ± 0.05 | 7.9 ± 3.6 | 92 | 86 | 102 | |||||
| C3bAx488: CCP 2 [N125CAx555] | 94 | 1.69 ± 0.06 | 9.6 ± 4.0 | 89 | 83 | 98 | |||||
| C3bAx647: CCP 3 [S199CAx555] | 66 | 1.46 ± 0.02 | 22.1 ± 2.1 | 75 | 74 | 77 | 0.52 ± 0.04 vs. 0.45 ± 0.04 | 13.2 ± 10.5 | 76 | 68 | 101 |
| C3bAx647: CCP 4 [N238CAx555] | 35 | 1.08 ± 0.06 | 42.6 ± 3.6 | 64 | 63 | 66 | 0.82 ± 0.03 vs. 0.51 ± 0.05 | 37.6 ± 6.8 | 66 | 69 | 63 |
| C3bAx647: CCP 4 [S254CAx555] | 45 | 0.49 ± 0.02 | 74.1 ± 1.4 | 51 | 50 | 52 | 0.54 ± 0.04 vs. 0.30 ± 0.03 | 43.8 ± 6.8 | 59 | 56 | 61 |
a
Distance (D) between Cβ of relevant side chains.
b
Weighted average of two or three individual lifetime (τ) components used to fit decay curve.
c
Average D and range, Dmin−Dmax, calculated from FRET efficiencies and associated experimental errors.
d
Average lifetime for donor alone (don.) versus donor plus acceptor (don. + acc.).