Table S1.
Summary of SAXS data
| Parameter | Sample | |
| PKI (0.5–2.6 mg·mL−1) | PKI Δ6604-6618 (0.5–2.1 mg·mL−1) | |
| Data collection parameters | ||
| Instrument | APS, sector 12-ID-B | APS, sector 12-ID-B |
| Beam geometry | Synchrotron | Synchrotron |
| Wavelength, Å | 0.866 Å | 0.866 Å |
| q range, Å-1 | 0.005 | 0.760 |
| Exposure time, s | 10 | 10 |
| Concentration range, mg⋅mL−1 | 0.5–2.6 | 0.5–2.1 |
| Temperature, K | 298 | 298 |
| Data collection parameters | ||
| I(0) [from P(r)] | 3.52 ± 0.02 × 10−2 | 5.27 ± 0.03 × 10−2 |
| Rg, Å [from P(r)] | 26.5 ± 0.2 | 22.8 ± 0.2 |
| I(0) (from Guinier) | 3.5 ± 0.1 × 10−2 | 5.2 ± 0.1 × 10−2 |
| Rg, Å (from Guinier) | 25.6 ± 0.3 | 22.3 ± 0.3 |
| Dmax, Å | 90 ± 5 | 75 ± 5 |
| Porod volume estimate, 103 (Å3) | 37.4 | 26.5 |
| Dry volume calculated from sequence, 103 (Å3) | 21.4 | 16.8 |
| Molecular mass determination | ||
| Molecular mass (Vc), kDa | 29.1 ± 4 | 24.3 ± 4 |
| Calculated molecular mass from sequence, kDa | 22.6 | 17.8 |
| Software used | ||
| Primary data reduction | IGOR PRO | IGOR PRO |
| Data processing | PRIMUS/GNOM | PRIMUS/GNOM |
| Ab initio analysis | DAMMIF | DAMMIF |
| Validation and averaging | DAMAVER | DAMAVER |
| Rigid-body modeling | Mc-SYM | Mc-SYM |
| Computation of model intensities | CRYSOL/FoXS | CRYSOL/FoXS |
| 3D graphics representations | PyMol/Supcomb | PyMol |