Table 1. Fit parameters and calculated equilibrium constants for tryptophan fluorescence titrations of CaM and MA.
The first column indicates the presence (Ca2+) or absence (EGTA) of calcium and the second column shows the concentration of NaCl in the sample (0–500 mM). The equilibrium constant Keq for each curve was calculated from fits to the tryptophan fluorescence data for CaM-MA in the program ORIGIN, with the fit quality described by χ2 and R2.
| Ca2+/EGTA | [NaCl] (mM) | Keq (M) | χ2 | R2 |
|---|---|---|---|---|
| Ca2+ | 0 | 1.71 × 10−7 ± 6.34 × 10−8 | 0.00137 | 0.99752 |
| Ca2+ | 100 | 5.01 × 10−6 ± 7.18 × 10−7 | 0.00045 | 0.99842 |
| Ca2+ | 150 | 4.34 × 10−5 ± 2.45 × 10−5 | 0.00035 | 0.98819 |
| Ca2+ | 300 | 1.06 × 10−4 ± 1.18 × 10−4 | 0.00009 | 0.98728 |
| Ca2+ | 500 | 2.80 × 10−4 ± 1.13 × 10−3 | 0.00004 | 0.97219 |
| EGTA | 0 | 2.80 × 10−4 ± 3.71 × 10−3 | 0.00002 | 0.98306 |
| EGTA | 150 | Below measurement limit | - | - |