Table 3.
Frequency, dissipation and mass shifts observed during QCM-D measurements of the assembly and interactions of a BamABCDE/POPC membrane tethered to an Au-DTSP-ANTA-Cu2+ substrate
| Process | Parameter | Interaction |
||
|---|---|---|---|---|
| SurA | SurA + Ptn | SurA + OmpT | ||
| BamABCDE/β-OG deposition | Δf3 (Hz) | −43.3 ± 4.2 | −43.8 ± 2.2 | −37.1 ± 10.5 |
| ΔD3 (ppm) | 0.7 ± 0.2 | 0.7 ± 0.1 | 0.5 ± 0.4 | |
| Δm (ng/cm2) | 1124.0 ± 201.8 | 1053.3 ± 67.7 | 957.9 ± 320.1 | |
| BamABCDE/POPC Reconstitution | Δf3 (Hz) | −4.9 ± 4.9 | −4.9 ± 10.7 | −8.6 ± 13.5 |
| ΔD3 (ppm) | −1.3 ± 1.1 | −1.2 ± 1.7 | −1.2 ± 1.4 | |
| Δm (ng/cm2) | −205.6 ± 129.9 | 96.7 ± 422.6 | −15.3 ± 216.3 | |
| Chaperone ± OMP interaction | Δf3 (Hz) | −12.0 ± 6.2 | −68.6 ± 40.6 | −22.8 ± 7.6 |
| ΔD3 (ppm) | 0.7 ± 0.6 | 5.4 ± 3.7 | 2.7 ± 0.7 | |
| Δm (ng/cm2) | 308.2 ± 196.7 | 1358.4 ± 815.7 | 553.1 ± 560.3 | |
All values are shown as the mean ± standard deviation of four independent measurements. Frequency and dissipation shifts are shown for the third harmonic (Δf3 and ΔD3, respectively) and changes in mass (Δm) are values estimated from viscoelastic modeling taking into account all harmonics measured. In the case of the initial adsorption of BamABCDE in β-OG micelles, values are given relative to the observed absolute frequency and dissipation values of DTSP-ANTA-Cu2+ functionalized substrates in β-OG buffer in the absence of BamABCDE. For subsequent processes, changes in frequency, dissipation and mass are given relative to that at the end of the previous process.